First, many local libraries offer digital check-out services. Call up or email your local library to find out. Secondly, insofar as a business idea? Publishers

First, many local libraries offer digital check-out services. Call up or email your local library to find out. Secondly, insofar as a business idea? Publishers already want to force libraries to constantly re-license eBooks after they've been check out X number of times. (As low as ten.) I can only imagine how they'd treat a for-profit venture. I wish you luck if you want to try this, but I imagine that magic number for price of subscription fees (first appealing to voracious readers I'm sure) and the cost for licensing book rentals would be tough to get right.