My opinion is that the Whites Goldmaster 3 is the best nugget detector under $1000. It's a learning curve but those that have taken the time to learn will tell you the same, it's the best. It will find small nuggets. I used to live in Las Vegas and would go to the placer gold fields in N. Arizona and found many small gold nuggets and even a meteorite at Gold Basin with this machine. I used to belong to the Gold Searchers of Southern Nevada http://www.goldsearcher.com/
It looks like the club is no more now that I look at the website but they had a lot of good claims back in the late '90's. Some people used the Gold Bug 2 and were quite successful. The Minelab SD series are the best but you're talking over $1000. I had a SD 2000 but always wound up using my Whites Goldmaster 3 or my Whites v/sat.
Here's some nuggets I found with the GM3, you know when you find the small ones the big ones will be no problem, but they're a heck of a lot harder to find. Feel free to send me a PM if you have any other questions on nuggetshooting. By the way that's an old copper penny I used as a reference to size.