Meh. Just sell a kidney to fund the bike purchase. Doesn't even have to be yours. Become a "broker."

When the time comes, make sure you get the bike fit to you. A lot of shops will do this for free when you buy from them, and the ones that don't, might be talked into it if you try. That will help a lot with your back. So will practice, though; like all things, you get used to it. At least that's been my experience.