I’m buying as many heirloom as I can, even if I’m not planting them this year...
Same here.
I am learning how to save seeds, too.
The key, though, is to not plant two varieties of heirlooms too close to each other or they will cross pollinate and the heirloom strain will be ruined.
For my onions, I tried to buy varieties of different days to harvest so there’s no overlap. They will come into flower at different times. I hope.