Classic "fear of the unknown". From your other post I can tell you confused on why a floor/foundation for a shed is going to cost more than shed itself ! Sorry that is the way it is !
Your alternative will just give you a muddy mess.
- Go to YouTube and start watching video about building a shed.
- Go to Home Depot or Lowes or Menards and buy a book on basic carpentry and one on sheds.
Number 1 rule of a shed floor is get it up off the ground and not just a couple of inches !
For your 8x10 shed, if you don't want to do all of the prep work
(remove sod, add stone dust/gravel, etc) then you need to be even higher. High enough to get light and air underneath
(that will keep the critters from thinking it is good place for their home). To me this means 2 concrete blocks high. The first one should be buried about half way in the dirt (the holes go up and down). Spaced every 2' that would 20 blocks for the first layer and 20 blocks for the second. Use pressure treated 2x8 every 24" on center
(so a block will be under each joint) that would be about 100 linear feet. 1/2" plywood will flex a lot, but if your not parking a large lawn tractor it, it should be okay. Going up to 3/4" plywood will cost about $50 more.
If you want to "cheat' and save money, use 1 layer of concrete block and pressure treated 2x6s.