How exciting! All the best with the new shop.

Re: the saddle library idea...
WTB produces a set of test saddles for bike stores to lend out. I think it cost the shop I went to NZ$600 to get a set (about 8 saddles, IIRC). From personal experience, being able to take these saddles for a test drive and bring 'em back wet and muddy and all is great. Made me spend twice as much as I meant to on a new saddle for my mtb, but the new one is so kind to my bum that I just don't care. Now, people coming in and spending twice what they meant to and not being bothered by it is just what all shops like...