Two ideas (we have both):
1. Golf cart with a bed on it such as:
Yamaha G2/9 Golf Cart Aluminum Dump Bed $500-$4000
2. Toro Workman MD/2100/1100 - (
Our Workman 2100 cost $1400ish)
The Workman has a 4x4ish (inside dimensions) bed and will haul around 1000# in the bed. The golf cart has a 3x3 or 3x4 bed and will haul 400# or so without complaining.
We have stacked 6-8 bales of hay on a golf cart (5 stacked 2 per layer in the bed and one in the passengers seat) and it worked well. My mother in law prefers golf carts to the Workman as they are much quieter.
Aaron Z