Let me start by saying I have been detecting since the '70s. I admit, I am mainly a cache hunter but I have prospected on GPAA claims across America and other sites. I am a GPAA gold life member.
OK now to the nitty gritty. For prospecting, I use a Whites Surfmaster PI. I have been using this same detector for 14 years. I paid under $1k for the detector. Now the question is, is it good enough to use for prospecting? Well, it has paid for itself many times over. I also use it to hunt beaches since mineralization does not bother it's operation. It is also completely waterproof. In operation, it is utter simplicity. You just set the two knobs to the preset positions and detect. How deep will it go? The deepest gold I have found was at 10". Well on the beach, It found a boat anchor at between 3' and 4'. It's hard to get exact in sand. There are 3 variations of the Surfmaster PI . I have the one that has the pulse delay control which I think is the best. There is a new version of this detector called the dual field. It has two coils wound in the same case coil.
Now a little about my cache hunting detector. it is an old Hays 2 Box detector that I picked used for about $250. It has found caches at 6'. It will pick up caches in just about any direction. As an example, you could walk along a stone wall and detect a cache in it. There is one detail you should know. It will not pick up anything smaller than a softball, but this is useful in junky areas where you are looking for a big cache. I have found some caches, but the big ones have evaded me so far. The thing about cache hunting is it takes a lot of research time. I am convinced that there are plenty of caches out there, but the pickins are not easy.
Now for my old reliable general purpose detector. It is a Whites XLT that I bought 14 years ago for under $1K. It has returned that many times over. This detector is easy to use and also infinitely adjustable if you really want to get into it. You can get into the computer and adjust just about anything. I fine tuned these settings when I got it and never looked back. It has programs you can select and go, like coins and jewelry or even a prospecting program. Yes I use to use it for prospecting, but it is so sensitive that heavy mineralization is picked up.
Now for the little hand held detector I use to check out walls in old buildings. It is a Vibratector and it has a small coil with a detecting depth of 6". Ideal for wall searching.
I bought it used for under $100. Yes it has paid for itself and more.
Well, that's my stable and all the 'ponies'.
Hope this info helps you out, Frank...-