MSRP on the BH Gold Digger is $99. Often discounted, and a good "entry level" machine for coinshooting. Not in any way comparable to a Gold Bug.
If you want to do real gold prospecting with a metal detector, you need three basic things.
1. You need to know what the heck you're doing. The book I recommended earlier is a good starting place.
2. You need a medium to high performance metal detector designed for gold prospecting. A lesser metal detector will beep if you chance to swing it over a large nugget, but large nuggets are rare. If they were common, gold would be $10 an ounce, not $1690.
3. You need to be searching where the stuff is. If there ain't no gold, you ain't diggin' any no matter your skill level or how much you paid for the metal detector.
--Dave J.