If you do all the grunt work yourself, you can do a bob surprisingly cheap.
Shorten the stock bed and stick with the original duals and front tires is THE cheapest way to go.
I did mine the first step that way for the cost of a used front Deuce suspension set-up ($250 plus freight), a new rear brake hose, welding wire, Sawzall blades and torch gas. I even reused the stock driveshaft.
After that, I went the HEMTT wheel/395 tire route.
This added to the above:
Gaskets and seals to flip the rear hubs (around $50-75)
Four modified HEMTT wheels ($275 ea. plus freight)
Four 395 XML tires ($175 ea. plus freight)
Four valve stems for the wheels (about $80)
New lug nuts (about $20)
It's hard work but the pay off is worth it ten fold.