I feel your pain. My tomato seed spreadsheet already had 399 lines in it, a few months back, when I returned to Tomatoville, and found a few new seed sites, like Heritage Seed Market..
Including the 25+ varieties I got from Heritage, and the seeds that were shared with me by some members here, I'm now up to 454 lines..
Granted, most of the initial 399 entries were 10+ years old, so some updating was in order..