This is a difficult question for several reasons. Finding a good programmer and finding a good programmer who's right for your project are two different things. If you want the best you'll have to pay through the nose but it sounds like based on your project you don't need a big hot shot, just someone with the skills that match your site idea. One thing would be to investigate a bit more and find out more exactly what you need.
You can find/hire freelance programmers on several sites (search for freelance programmer), check out people's ratings and other jobs to see if what they do really matches what you want.
As far as price, this varies widely by geographic region, but then again you might be better off paying someone from the US twice as much because it might be the case that the job will take half as long if you're working with someone you can communicate better with.
Here's an interesting page about rates:
[bostonphp.org...]
That says the average PHP freelance rate in Boston is $65-75 (and the 'rockstar'/super-coder rate is over $100/hour). That survey isn't very scientific but for a good programmer you should expect to pay a good hourly rate. An experienced coder will get things done better and faster so they're worth it. If you're willing to work with someone who's just learning though and deal with those issues (job takes longer, messier code, misunderstanding of requirements, etc) you can probably pay someone (college student?) significantly less. In your case this might be appropriate since you're not sure if the site will not make any revenue. You can always try advertising in a local college newspaper or craigslist.