Sorry to hear about your injuries man, that sucks you have to end your season. Best of luck with the healing.
The diamondback recoil looks like it would fit your budget well and your requirement for a 29'er, however it is most certainly a XC bike with the 100mm travel front and rear. That will have you feeling fairly beat up after a DH day and you will have to pick your lines well but it is certainly do able.
Depending on what your trails are like I would probably look into a 26" AM bike with around 160mm travel for a more downhill capable bike while keeping the ability to ride uphill. There are a lot more options in your price range for those in the new/used market.
Check out Pinkbike.com's buy and sell section, there are some killer deals to be had if you can sift through the BS.