Likely not available but even if they're not, repairs can usually be made as long as it's not deteriorated by corrosion. Typical repairs might involve replacing a seat washer, packing the stem, lubricating the stem, and finally replacing the seat. That would be the hardest thing to find and match, so you need an old-school hardware store with drawers full of them. You remove the one you got, if you're at this last resort stage, and size it exactly. That's the only way to do it.

Handyman here. Just replaced a shower valve today with different circumstances, but similar to what OP is talking about. My 2 cents: 1. Trades people will most likely charge more than you think they should. This is due to many of the things people already mentioned in this thread, but also because you bought the material. Trades people often have products they like to work with because they are familiar with them. Familiar with how they install, how they perform, how they function. When you provide materials, you also remove one of the ways they pay for their cost of doing business - markups. You can judge the practice of marking up however you'd like (just like some people don't like tipping), but its standard throughout every trade you are ever going to hire. Some people are transparent about it, some are secretive. Either way, it's how everyone pays for the cost of providing any semblance of a guarantee. 2. There will always be a spread of cost for the trades. Think of it compared to a whole house - at some point, someone is going to build a house that is less expensive in order to sell it faster or more often. The only way to do that, is to compromise somewhere. That price compromise can happen in the quality, profit margin, or speed. The race to the bottom sinks all ships. When you undercut the markets evolved price, you cannibalize small business (think about Amazon compared to small local boutique shops, toy stores, or anything non-chain). If you take a loss, you wont stay in business. If you hide cost cutting measures, like hidden poor workmanship or speedily done work that will not last, you might win in the short term, but your reviews and your customers will reflect that over time. If you are able to outlast everyone else, run at a loss, and own the whole industry - well thats not good for anyone except you. 3. Costing more often means more value. The person may have been a poor salesman, but I would wager that they provided more than their competitor - cleanliness, documentation, warranty/guarantee, etc. 4. Understand that often a quick quote will be some standardized cost that the company or person is confident they can make a reasonable profit with over time. This may mean that jobs like yours, while simple seeming to you, sometimes are more complicated than anticipated. Yours may not have been, but the next one down the road might take a whole day and they would loose money. The subsidized model is similar to the way insurance companies price their products - obviously different in other ways since it's not a subscription model. To those other people in the thread saying things like: "spare me the overhead' or "its on youtube, DIY it" or "my friends a master and says it should cost this" You should be cautious when telling other people how to run their business. Your assuredness and sometimes smug responses, while protected by the anonymity or distance of online communication, it doesn't protect you from forming poor mental habits filled with logical fallacies. You come across as arrogant and ignorant. Imagine everyone one you've ever met in your life - that's a garbage sample size from which to pull an opinion when you speak to the crowd of the world online.

I am not a professional but it seems like a penny wise/pound foolish decision not to replace as much as possible when you are doing a major renovation. Everything has a useful life so at some point I would assume you would need to replace. I remodeled relatively recently but prior to that I had to replace a cartridge and it was an expensive plumbing job. As I recall I also felt lucky that the plumber was able to find something that was compatible - ugly but compatible :-). Also - although you didn't mention it, since you are complete remodeling anyway, you wouldn't be limited to Moen fixtures that fit the existing plumbing.

I had another go at getting that chrome cover off. It was silicone'd in place :) Looks like my mixing valve is connected with PEX for the Hot, Cold and up to the shower head. The connection down to the tub spout is soldered copper. The other side of the wall is in a laundry room and the wall area is clear. I did find a video that showed the procedure for cutting the wall and replacing the mixing valve. I am not sure I want to tackle replacing the valve at this time. That's a good project for when I have a whole day available. I would have to borrow a PEX tool. I wonder if the threaded on connectors could be spun without cutting the PEX? Would that destroy the PEX seal? I have all the pipe soldering tools and copper pipe fittings. Here's a couple pics of the round brass valve/mixer and the valve itself. You can see the PEX connections left, right and up