Cardcomm might come off a little demanding but has some great points; a quality developer is going to have an open dialog and will offer recommendations to give you the most bang for your buck. A code monkey will say "yes, yes, we can do that, yes" to everything just to get their foot in the door. Focus on the core features, the experience you want to give the user (craigslist plain and simple), and budget. Inform the developer you have intentions for scaling this project in the future, but scalability is not your focus. (Most sites can scale well, unless you're building the next facebook).
QuantumKiwi is spot on with the 20-30 range for a code monkey. Occasionally, this is exactly what you need; particularly if its just a small utility for yourself. Take advantage of this if you need something right now and are willing to throw it away when you have more capital to do it right. (Never build on a code monkeys project; start fresh). When it comes to a public facing site you'll definitely want to invest in a quality developers/designers.
I work as a professional web developer (mostly domain layer) and I can assure you a competent developer can be found for far less than 160/hr. I would argue that the type of project you're looking for, you can find someone in the $60-80 range. I would recommend spending a little extra money on the design of your site. Its the designers job to make sure its laid out intuitively for the user, the color scheme makes sense, branding, and all that good stuff. A user will accept a broken feature or two, albiet annoyed, but they won't accept a butt ugly site. Its easy to fix a bug, its difficult to rethink the design.
Also, when you get a rate and an estimate on the hours, figure in an additional 10%. There's probably a few extra features you'd like in it before go-live. Scope creep happens all the time and project owners always seem to forget to factor it in
Good luck. [Btw, Cardcomms insights are exactly we look for when hiring developers; its easy to teach someone how to code, its difficult to teach them how to think.]
