I don't like talking about what my bikes cost because I'm just a year out of grad school and I don't like when people make assumptions about my financial situation based on what I'm riding or driving or what my DH makes. That leads to them making assumptions about whether I need to work at all, which I do, and it's quite annoying.
If they are asking about my Dahon, I tell them what it retails for, and if it seems that they're really interested in the bike, I'll use it as a segue for for how I have a friend at the company and that I like that the company is dedicated to promoting folding bikes as _part_ of the solution to making transit multi-modal, and that they have a whole range of bikes at various prices that are geared toward different types of riders/functions.
If they ask about my Rodriguez, I tell them that my insurance policy picked up about 2/3 of the cost, which is true. Rodriguez is pretty well known locally so we usually skip the "how much did it cost" part and go straight to the "how can you afford this" part. Which is odd, because as others have mentioned, there are FAR more expensive bikes out there. Rodriguez bikes are actually quite reasonable, given the challenge of finding a good fit for someone who is barely 5'1"
If people want to make judgments about me based on what I spend on my bikes, I tell them that as a petite person, I REALLY don't have a lot of options. I've since learned about a few more since joining this board (Surly LHT! Coveting it!), but I also don't need another bike right now.
My theft-proof GT Rebound (Doesn't matter what it cost, 'cuz I'm sure I can't pay anyone to take it off my hands, which is fine, because it is dearly loved) is crying out for some TLC.

