Nice hearse! Instead of pexi, maybe you could use polyvinyl fabric. It's a heck of a lot cheeper than plexi.The wheels are from harbor freight. Its best to wait till they go on sale. Also some wheels have tighter spokes so if they will let you open the box and check them first.
I do want to do plexiglass but the price on large pieces is outragous. Not so sure on glass though. I was thinking of mounting a flourescent fixture to the inside of the roof for a black light. Then hanging short white curtians that would glow. Or perhaps white washing the coffin that will go inside so it will glow as well.
Walmart used to sell it in their fabric department. Heres a store that has it. Clear Vinyl