I have done alot of research on the internet and through members of my Gold Prospecting club here in Colorado. From my opinion this site has the easiest, most efficient homemade gold prospecting equipment and plans you can find! I have used Keene Highbankers, other homemade equipment, and panned for some time now but if you take the time to build one of these I think you will be happy with it. Just an idea...here is the link.
My partner and I built a highbanker in the garage last winter. It did quite well during its first full season. I was build without spending a great deal of money. The hopper is manufactured from an old file cabinet, the base from schedule 80 pvc, the sluice was bent at a local boat builder's shop for a 12 pack, the riffles were stolen from a couple of old hand sluices I had laying around, and the pump and motor were bought used.
If you want some more information I would be glad to help out. If you have built a dredge I would love to hear some of your ideas. A dredge is this winter's project.
Here is a link to my website. There are other mining pictures here.