CO2 tank is the way to go. I have a 20lb tank that will last for years on 1 fill! I think fresh kill gives you the safest (vs feeding live) and quickest (vs thawing) way to feed. It will also allow the OP to continue to support his local mom and pop store if he would like. The other benefit is that if the snake goes off feed for that day you can freeze it and save it for the next feeding. This is a win all around. I currently breed my own rats and supplement from a local pet and garden center. This works great for me. It is a bit more expensive than ordering bulk but the fiance doesn't want a freezer full of rats either lol.