You mentioned 3 family members and I was assuming you were arming everyone with 5.7. Anyway, I definitely got into the 5.7 game late, but I'm still glad I did. That Ruger 57 is a blast and 20 rounds per mag makes it nearly as fun as the PM -30. Wish me luck on finding a PS-90.I grabbed two because that is how many hands I have. I think I have one or two more.
As you might guess, I buy ammo in large quantities - driving 30 minutes into town on the off chance I can get 100 rounds of ammo just isn't worth it for me, not when I already have plenty. In 2017 I paid $18/50 of SS197SR (40 gr VMax) and $16/50 for FMJ from PSA, and I got a lot of my ammo with guns I bought so I did get it fairly inexpensively. A lot of the ammo I've seen advertised is close to $1/round.