I have a used Minelab Musketeer Advantage that is a solid machine. It goes as deep as most of the big dogs, but has less discrimination against trash (and the feature known as "notch" that allows you to blank out specific problem items like pull tabs or bottle caps that can be heavy in some sites). It also has no visual display, but the audio gives enough clues to make up for it when you get to know the sounds. I paid $225 four years ago, and it came with an extra coil, "hip mount" shoulder bag, NiMH batteries and both a wall & 12V charger. I highly recommend that one if you can find a used one. Little to go wrong if it's not battered around.
The Tesoro detectors are good and they have some relatively low cost models (the Compadre I think it is, for like $150). Fisher has a very similar 1212-X. The standard now seems to be Garrett's Ace 250 for just over $200, which gives a video display, as does White's Prizm II for the same $. I would avoid any detector that gives a single, modulated "belltone" for every hit. You want one that gives "real-time" audio so you can judge whether it's a smooth, even tone or a clipped, chipped ot chirpy signal that usually incates trash (especially foil). There is a big following for Bounty Hunter but I really know nothing at all about the brand. Best way is to get somewhere to try a couple out.
Here's a site to get a flavor.
http://metaldetectorreviews.net/
The features you get with added $ are not necessarily more depth. But definately better abilities in trashy sites, mineral soils, disturbed soils, etc. You can find quite a bit with a low end detector if you dig every signal and figure the trash is part of paying your dues. Lots of guys miss good finds because they (or their machine) misinterprets a signal.
Good headphones will make a world of difference, too.
