I found a cheat for the Equestria Girls app cause I'm cheap.
If you can find a big image of the girl you need to scan with necklace (just google search "Equestria Girls Friendship Games Doll" and the doll you need), you can scan the image and it'll register. Mostly - it's a bit picky, but I've played through about 3-4 companion quests now and not needed to buy any of my girls.
And now I can spend my gems on more important things - aka, clothes. XD
EDIT - Figured I'd make thing super easy and upload any scan code pics I have.
Here's what I have: http://sta.sh/224awtnw4ahn?edit=1
I am looking for the codes for Photo Finish, and all the cod