Mistbind Clique and Spellstutter Sprite aren't exactly budget but if you are ok with 1-of's I might try them. Faerie Harbinger can help you find those solid 1-of's and is monetarily inexpensive. Cloud of Faeries , Glen Elendra Liege , Glen Elendra Pranksters , Latchkey Faerie and Nectar Faerie are all blue/black options. Not sure what style you are going for and I'm not an expert on the faeries but I'll do what I can.

She said "evil magic and mind control" but she also wants it to be fairies.

So fairy/rogue is what I think I'm going to go for.

Not really much of a style, I just want decent cards in the deck. She will never be bringing this deck to any event EVER

Thanks for the suggestions! Faerie Harbinger is great!

Please more suggestions!

A quick search on gatherer and these might be evil and helpful:

Faerie Impostor , Faerie Swarm , Final-Sting Faerie , Glen Elendra Pranksters , Knacksaw Clique .

You could maybe add a sac outlet e.g. Carnage Altar . Trying to abuse the Sower of Temptation or other ETB faeries. When I hear evil faeries I think they will steal my stuff and kill it, then flicker or bounce Sower of Temptation to repeat said evilness. They would also be easy ways to learn and practice some of the more intricate plays in MTG.

And I think all these faeries are rather cheap, so they're right up your alley.

I mean if I didn't have my promo Oona, Queen of the Fae in other decks I'd give thme ot her. maybe I don't need two?

Muddle the Mixture may be a better choice than the counterspell I currently have? Besides flavor of course