Naw best bet is to stay away from cheaper low end ones or older detectors. They have came a long way in the last 10 years or so.
Stay away from any Radio Shack or Bounty Hunter machines. Tesoro are ok machines for low end machines but most of the other brands will walk circles around them in depth.
Whites makes a few good machines. Pending on what you want to do; look for old coins, relic hunt, beach hunt, or just stay in school yards. In the Whites line I would consider the MXT or V3 models. The DFX is a little too complicated; too many settings depend on one another to work right. The TDI is their cats meow but its costly. Stay away from their other machines...you'd do better with a stick and a magnet attached to the end lol.
Garrett has came a long ways in the past few years. They have the Ace series which is good for coin hunting modern coins but their new one is the A/T Pro. I'm hearing it is okay in good soil but not so great in mineralized soil but would still be one to look at in your price range.
Fisher/Tecknetics are the same company. The Fisher F series are good. Stay away from the 1200 series. They are old technology. The F Series are what you want in the Fisher line....the F5 or F70 would be good choices for you, or a used F75. Tecknetics has the same machines as the Fishers...just different name on them. Their Omega series are good and the T2 is the equivelant to the F75.
Minelab is out there too....their XTerra series are what you will want to look into in their line. Their high end Explorer detector is okay but the XTerra 705 is just as good, lighter weight, and goes deeper to be honest and is cheaper.
None of the other manufacturers are worth looking into IMO. I've owned all the above high end models with the exclusion of the new Garrett A/T Pro.