Gday, it depends on what you want to hunt for.
I have a Fisher f75 wich is great for jewellery and relics, on the beach etc. Its also reasonable on gold nuggets as you can ground balance it. Our ground in a lot of parts is mineralised so it sends the detector crazy unless you can balance the unit to changing ground conditions.
If you are strictly after gold nothing beats a minelab gpx 5000, but they are $5000+
Cheers
Mike