I hope you and your brother are willing to throw out 10k because after the cost of the tramp, the pit you have to dig, and the pads that are need to surround it, your going to be broke.
Get an affordable tramp with a net (size 10x17 frame with 7x14 bed.) you'll only pay around 2k in total and you'll get a much more affordable option. I have one of these and its good enough to get dubs without double bouncing.
Also, look for an open gym in your area. You get to use their sick equipment for probably 10 or 15 bucks.