The tires were from HF on sale at about $8 each. The forks were purchased from the Kubota dealer for under $50 for the pair.
The tires from HF came with a set of straight forks that can be bolted to something, no swivel. Normaly these are about $15 each if memory serves correctly. I've seen them at TSC as well but a little more money.
The Kubota forks are basicaly factory. I did have to spread the forks about a 1/4" or so with the porta power and drill the bolt hole a little bigger.