I should clarify (for the uninformed) that I found that I can get an RTA cabinet, including shipping, for roughly the same price as a big-box store, in-stock vanity. I have been looking at white shaker styles, but am open to other styles--just so it is true white. I'd love one with drawers, though that is hard to find in a 24" vanity. ( I don't want to spend more than $250 max on the cabinet, and preferably closer to $200!) I can find all sorts of gorgeous, high-quality vanities online, but can't afford the already-assembled ones. There are quite a few even on Lowes and Home Depot's sites that I can't afford, LOL. Thanks.

I didn't know these existed, so I am sorry I have no experience to share but thank so much for brining it to my attention! I googled RTA bathroom vanity and found some very attractive choices. I hope someone here gives some feedback on some source, for both of us!

Thanks everyone. Well, I found out that J & K cabinets (a large RTA cabinet distributor) had a local dealer not too far from me, (Global Home Products in Beltsville, MD) so I called them and they actually had the size and color vanity I wanted in stock. The price was $199, and assembly was only $10, for an all wood, painted white shaker style vanity. Even the center panel on the doors was solid wood --a true reverse raised panel (almost every RTA cabinet seems to use MDF for the center panel!) The cheapest, similar, special order cabinet from Home Depot or Lowes would have been between $300-400 (American Woodmark or Kraftmaid, etc.) I checked with Barker cabinets (an American made semi-custom RTA cabinet) and they were quite expensive in comparison.
When I got to the dealer, I was surprised to see what a large showroom they had and how busy they were, even on a weekday afternoon. I believe that all their cabinet lines were RTA, and they had very good prices. The display kitchens and vanities looked very nice. The place seemed to be run mainly by Chinese people, ( a little hard to understand their accents, but very nice and helpful) so I imagine they don't have any problems communicating directly with those factories that make their cabinets over in China if they need to!
Anyway--I'm glad that I had them put the cabinet together, as when they opened the box there was some minor damage to the face frame part. So they used the face frame off the identical vanity that was on their showroom floor and were able to assemble my vanity. It does look gorgeous--esp. the doors.
Even the back is solid plywood with wood bracing. I suppose that makes it more sturdy, but it will be more work for my husband to drill holes for the plumbing.
Hope this helps someone else who might be wondering about RTA cabinets.

By the way, I have seen this particular J&K vanity online for $168 with $36 shipping, by the way- so it was about the same as I paid for "brick and mortar store" retail. (In case someone wants to order something similar online.)

99% of the cheap RTA cabinets are Chinese sourced. The biggest issue with Chinese sourced stuff in the lack of any standards that are enforceable as to the quality and safety of the materials that they are made from. I've seen "plywood" in these have big voids, and stink to high heaven of formaldehyde. (Anyone remember the whole Chinese drywall debacle?) I've also seen the paint on the surface rub off with just a plain dishrag dampened with only water. (Remember the lead painted toys?) In fact, that's consistently been the biggest failing with all of the Chinese cabinets. Their finish work is substandard to even a budget American line.

I hope your vanity is decent quality. I really do. But, there is zero way to guarantee that that is the case, even with a visual inspection of the goods in question.

You raise some good points, Hollysprings. I did ask the company (J & K) about the formaldehyde. (I didn't think about the lead paint issue!) They did say that they are CARB certified (meets California's strict requirements for off gassing, air quality issues, etc, ) and NKBA certified. Hopefully we won't have any issues. The paint is supposed to have a clear sealer over it. I will try wiping it with a damp rag to make sure the paint doesn't come off before I install it!!

I'm not sure why China does seem to have so many quality control issues. However, when you are on an extreme budget, like I am, you appreciate their low cost and are willing to sacrifice a small bit of quality (though not where health might be of concern, of course) and having to "pick through boxes, etc. " to get a "good one"!

I'm old enough that I remember when "made in Japan" was synonymous with "cheap junk" (early 60's). They've certainly come a long way! Hopefully the Chinese will improve their quality over time.

You get what you pay for. Its not that the Chinese are incapable of making good products. They can make good products if the factory owners/wholesale buyers are willing to pay a premium for good quality products. However, everyone loves a good bargain, so most of the time people just want something for as cheap as possible while paying no attention to safety, worker rights, and environmental impact. Its a vicious cycle of "who can make this the cheapest".

I was curious, so I did a little checking.

BTW, the NKBA doesn't certify cabinets. They are a professional membership organization and neither Global nor J&K are members. They also are not members of the KCMA, which does test the quality of cabinets and certifies them. They do NOT pass KCMA testing. Given the lies that they told you, I'd not bet the farm on them being CARB compliant either. It would be hard to do if they won't pass KCMA.

Here is a link that might be useful: KCMA Certified Manufacturers

Here's another thread on J&K.

Here is a link that might be useful: J&K review

Thanks again, everyone. Thanks, weedyacres, (love your user name, btw--sounds like a description of my property!) for the J & K link. It was a bit reassuring.
Hollysprings--thanks for the link to the KCMA certified membership list. It might come in handy and I would be more concerned if it were a kitchen with tons of cabinets. Right now, I am just glad to have plywood sides and a painted finish instead of particle board and thermofoil in my budget. For a whole kitchen, I probably would want better quality or at least put together a bit better.