My girlfriend got one last week for $100 (Straight Talk, no contract, prepay). Bright but fairly low resolution screen, low res camera, pretty hefty battery that should go a couple of days on normal usage. I don't believe in paying much for phones--I'd never carry insurance or want to pay so much that I'd break a sweat if lost or broken. I paid $70 for a Moto E4 with Boost. Same general screen but better camera, Gorilla Glass and a bigger battery, plus Nougat rather than Marshmallow, but no replaceable battery. Think the J7 was going for $50 last year on Black Friday. God knows what the post trade war prices for these things in a few months.
To sum things up. Her J7 is a totally usable device that should give her a couple years of good service for about $4 a month.