Hi Joe,
Nice stand you built for yourself. Kinda looks like the one I made from a 2x12 and some plywood. You kinda over engineered the base mounting. The slots with the square nuts and the notching for the base supports seems like alot of extra time and labor . I think it would look cleaner if you just drilled and taped 2 holes for each base support. If you are really serious about offering this type of stand for sale list it in the vendor section of this form. If you want to find out what its worth, auction on e bay will give you an idea.
The stand you made turned out very nice. Alot nicer than the one I made out of a 2x12 and some plywood.
I 'm not trying to bash your work I'm just offering some advice that might help the value.
If anyone wants a whizzer engine stand made from a piece of 2x12 and some plywood? Look for it in the vendor section, there selling for $19.99 +shipping some assembly required and yes it can be disassembled for easy storage