It sounds like you want to buy DB to make money off of D3, then no, it's not worth it. Can't sell/trade shit in D3.
If you want to use DB to get super levels, then probably not either. A friend at paragon 800, bots 24 hours a day doing key and normal rift runs, gets 1 or 2 levels per day only.
If you want to use DB to help you play boring games farming mats, rift/keystones or uber keys, then yes, it's worth every penny.