PLEASE HELP !!

[ancientman]

Hi , BEST hunters !
Which is the best handheld ,proportionaly,small image device with 3D software that capable to detect caches of gold & silver coins (20-30 pieces) and for cavities at depth of (4-6) feet ?
-the soil is dry and rocky
-the site is very scrubby.The OKM Rover series ,Examiner,Accurate Locator Multi Sensor Pro Art seem suitable ,but I am not sure about and some are expensive .
One notice : When I said small device I meant not as GPR's big antennas or units .
PLEASE HELP !
REGARDS

[ancientman]

I don't mind if expensive techniques grant my request .The most important is that device really work and serve the required .
I like how look the OKM series techniques and how the company demonstrates it's competences ,but there is much debate about.
So I'll be grateful if you can recommend me the best but not bulky techniques .

REGARDS