Hey Matt - I'm in a similar boat as you, but with a bit of a twist. I like to purchase large collections and sort through them. A small part of me does this to see if I can happen upon a Trout rookie, and a much bigger part of me does it to find inserts that aren't scanned on here. After I'm finished, I usually organize them by team and ship them to people who collect according to team.
Thus, I'm letting you know I have several team cards for every MLB team (many fewer of the expansion teams), and I was wondering if you were interested. I'm guessing (with this new batch) that I have around 1,000+ cards per team (inserts, die cuts, etc. included). Let me know if you're interested and I'd be happy to sell some to you for next to nothing (like a penny or two per card).
Also, to help with shipping big quantities, I follow WaxPack Hero's guidelines pretty closely. That would give a good estimate of cost of shipping (website below).
Stay well, and I hope to hear from you soon!
~Brandon
https://waxpackhero.com/blog/the-definitive-guide-to-shipping-sports-cards-via-usps