I would say for sure use CoW and Early Church. Not only do you get the most bang for your buck in terms of playable cards, but people have a shot at getting a high $ UR like Shipwreck or Second Coming. If you start with those, then add maybe 3 foil packs, that gives you a draft of 60 cards which is pretty decent. Depending on what kind of deals you can get packs at, you can easily make the draft $15 and not lose $ as the host. Another option to consider is to allow people to bring their own foil packs to use to reduce the cost (for example, you allow people to bring their own 3 foil packs and only charge them $10 for the 2 box packs, if you get the box packs for $4.50 from 3 Lions, you come out a bit ahead to help pay for tourney fees).
