since its all put together with carriage bolts, you can just drill a hole at another part on the horizontal board, and bring the two sides closer together, making it steeper
and as far as price..lets see, 4-10ft 2x4's, and maybe 9-8ft 2x4's, and a whole bunch of screws and 12 4 inch long 1/2 in. thick carriage bolts, and the plywood for the front, and i used decking for the top, so i will try to calculate the total real quick