I have two pairs of baby flip flops. One is Havaianas size 17/18 (website says this is a 4/4.5 infant size), worn once. The second is Baby Gap, size 3-6 month (NWT).
I honestly don't know who puts their babies in flip flops (my babies hated them!), but people really like giving them to us! If you like flip flops on your babies, I will send one or both pairs to you for cost of shipping (should be less than $3).