OP writes - I got 10 8ft long 2x4's and two sheets of OSB at just under 1/2 inch thickness. The OSB sheets are 8 ft x 4 ft, so I just had the guys at HD rip them in half lengthwise and it gave me four pieces at 8 ft by 2 ft. I also bought a box of 2 inch wood screws, and it totaled $56 dollars. The only thing I didn't buy were the 2x4's for the middle and end supports, so if you have to by those this project would be just about $60! Not bad.
Don't waste all that space between joists in a basement or garage. Screw wire shelving to the underside of the joists. Use a standard 8-ft. x 16-in. length of wire shelving and a pack of plastic clips, or have it cut to length at the home center.