Hey Miranda,
When I was looking at bikes, my LBS had to order one in my size for me to test ride. I put down a deposit of $50. I ended up buying the bike, so the $50 was taken off the selling price of the bike.
As you mentioned, the LBS is at some risk of having to carry inventory if you decide not to buy the bike. I think a reasonable deposit, which is refundable if you buy the bike, is a solution that works for both parties.
Good luck in finding your bike!
- Melissa
I'll get back on the bike soon, I promise!