Starting Up a Small Single Room Library for a Non-Profit: Oh Where to Start...

Hello Library Gurus,
The Space Foundation announced the establishment of the Zimkas Space Library, honoring a really cool guy who has been a tireless advocate for Space Foundation endeavors for over 27 years! Currently, all the furniture and shelves are in place. It looks great, with tons of donated books in piles all over the floor while things get "cataloged" and shelved.

I'm not an active part of the library setup right now, but found the location to be a great post-eating hangout. As a developer/designer (with Drupal used everyday), I couldn't help but ask if there was a system in place to catalog books and check them out, etc.,.

... The magic all happens in an Excel spreadsheet ...

A spreadsheet could work for now, but I'd like to brainstorm on how that can be managed more efficiently in the future. I was thinking about whipping up a basic cataloging site that integrates with Google Books for quicker adding of books, and manage library users and checkouts from the site as well. As a bonus, I could recycle a mobile app I'm making that delivers bonus museum artifact content (from Druapal site) via QR codes to checkin/checkout books that have codes on them... I think we even have a card printer handy for printing membership cards.

What do you think? I'm really naive when it comes to managing a library. This goes along with everyone else at the Space Foundation. Everyone has their excellent skills, but managing a library kinda came out of the blue.

If you had a room full of books, would a spreadsheet suffice (Am I over-thinking it by wanting to create a Drupal site)? Is there a Drupal setup already out there that is not overkill, that would help checkin/checkout books and manage a catalog on the cheap (no additional Library catalog software or library scanners required)? Should I create something custom sometime this year? Would someone bored like to volunteer for this (never hurts to ask, right?). :D

Thanks for the feedback in advance! I truly appreciate it.