The Whites Prizm V is your choice or the Quantum Pro, you will appreciate the Visual Target ID, Tone ID, specially the depth gauge and the pinpoint, the 9.5" coil is great too.
You can also try eBay and try to get a Whites XLT E-series or a DFX, the Explorer II is an amazing detector (or the Quattro), if you can find one of the two Minelab detectors I mentioned on eBay go for it!
And to start you'll need just a few things, trust me on this one, Try getting a 'Sierra Dig-it", a "Treasure Scoop", a 14" trowel (again, from Jimmy Sierra), a Convertible Twin Scoop (From Jimmy Sierra)for when you're on the beach (works amazingly), a pouch to keep the dug stuff, a big piece of cloth (to put the dirt you scoop out) it won't cost you a cent. An 8" probe. That's all, oh, and if your budget allows try getting a bullseye II pinpointer, I have the bullseye (the first one) and it works great, the Bullseye II has a vibrating option which is great if you like keeping your headphones on. Here's where you can get all of your detector accessories:
http://www.jimmysierra.com/
Hope this helps, and yes, I have everything I posted so I can reccomend it! I GREATLY reccomend Jimmy Sierra accessories!