estimage the weight of the shed:

1.lumber: ((8+10)*2*3/4+6*2)*10+(36/4+4)*45=945, cost 400

2.shingles: 1 square=240 cost 120

3.floor: 200. cost 150

4.siding: 100 cost 200

total: about 1500 total cost 1000

The lowest weight bearing clay has 2000 lb/sqf capacity, so you can go with 4 stacks of cinder blocks into the ground, one at each corner.