I absolutely will not install a plastic pop-up assembly. If someone provides their own faucet (which I will not warranty) and it comes with a plastic pop-up assembly, I tell them that they will have to pay for a replacement or get someone else. I say it very nicely of course, and explain to them why it must be done this way and how they will thank me later (or probably won't thank me later because after it's installed they won't ever have to think about it again). This is another reason I hate dealing with box stores, people go in there not having the first clue about what makes for a quality faucet, toilet, etc. and then call me to install junk (this is not to say that everything contained in a box store is junk, but a lot of it is). If I'm willing to do it at all I tell them that it is not a very good product, what sorts of problems they might expect, and that I will not warranty any product that I do not provide.
As for the cost, a quality, low end, single or double handled, chrome finish faucet will cost $250.00 installed. That's $100.00 for the faucet [(cost + tax) X 2] + $150.00 for the install. It will include the faucet w/pop-up assembly, 2 new supply tubes, new plastic trap, and a limited lifetime warranty on parts and finish w/2 year warranty on labor.