Like sl says, just wonder in a few places and try the classes, don't sign up for the first club ya walk into, try and get a bit of experience of all the possibilities first.
I imagine you've had a good look around on the net already but if martial arts sites and search engines don't come up with much you could always try town and/or city council websites (or US equivalents) which very often have a page for local sports clubs and contacts including martial arts.
With a bit of luck you'll find a dojo teaching a style you like and (more importantly) with people you can get along well with and feel comfortable training with.
eg. Would you prefer 2 hours of fighting and self-defence techniques or 2 hours of "how to focus your CHI energy (b*ll**ks)"
probably £5 at most per class, but a lot of 'decent' places will charge per month, at around £30-£40/month for unlimited classes, obviously you'd have to convert that into USD.
If they're offering 50p per class in a church hall, then be a 'little' wary, they're prob really good at what they do, but obviously not that good at running a professional club if they're still in a church hall.
You get what ya pay for, so don't just automatically go for the cheapest option.