I love you all too!
Anyways, if I weren't selling anything or if someone else comes along looking for a similar answer...
I would generally say to start at the bottom and work up, with emphasis on more popular, carrier-locked models. the Lumia 520/521, 530, 635, 435/532 are good starting bets of phones to look for. You're going to be looking for used phones.
Also other manufacturers are fine choices too, you may be able to snag a BLU Win Jr for a low price but it all varies.