Just discovered a way to upload that photo from bluebath.com

Remove one of the cartridges and take it to a plumbing supply place, OR even Lowes/Home Depot have extensive parts catalogs you can order from, complete with life-size pictures for comparison to your part.

If you have correctly diagnosed the problem as a bad cartridge the trick of the trade is to replace it with the manufacturer's EXACT replacement part and move on to another project.

Sometimes cartridges can be gingerly disassembled and o-rings replaced and sometimes they can't and sometimes new o-rings fix a leak and sometimes they don't.

If you find a third party cartridge that says it will replace the manufacturer's part number then there's a good chance it will leak cause most third party parts are close to OEM specs but not exact.

Since you found the cartridge at reputable sellers like Amazon then the price is what the market will bear and you have to decide whether that price is worth paying and being done with it.

Buying a new faucet brings it's own complications and whether it will be equal quality and style and longevity with less expensive replacement parts as what you have are questions that time will answer.

I've used the place below numerous times - walk in, not mail order - since I live in the Chicago area. They do have an 800 number to call if you can't find what you are looking for on their web page. This place was recommended 30 years ago to me by a neighbor who is a plumber. They've been in business for over half a century at the same location and have faucet and toilet parts going back 100 years.

As posted above, you should look to get the exact replacement parts. Two of the drawbacks of designer faucets is the cost of parts and their availability. That's the reason plumbers recommend Moen, Delta, etc. That doesn't mean designer faucets shouldn't be selected. It's just you have to prepare yourself for these issues when it's time for repair.

Here is a link that might be useful: The Faucet Shoppe

Thanks so much for the feedback! I tried the faucet shoppe and, sadly, Whitehaus is one of the few brands they don't list on their web site. Based on your recommendation, I may try calling them to see if they can find it somewhere for me.

I have replaced o-rings and disassembled, then re-assembled my faulty cartridge. It looks like the problem is a piece of cracked plastic, so I think the whole thing needs replacing. Big bummer, though. These things are expensive!

Thanks so much for all the help!

The faucet is actually made by Paini SpA Rubinetterie which sells replacement cartridges. Customer service: (856)881-7890. Don't know that they will be any less expensive.

Paini usually uses cartridges from Studio Tecnico Sviluppo e Ricerche (STSR) S.r.l an Italian cartridges manufacturer. You might try there.