Stay away from mineral oil, it will make your baits tough, soybean oil may cause them to foul over time.
You normally only put 4 drops or so in a bag of baits, so you don't need a lot. We went through quite a few testing them until we settled on the one we sell. It has good lubricity without an oily feeling. Unless you are doing something else with it or making a ton of baits it should last fro several months. As a side note, we also have a larger size bottle that we will be offering soon.
Jason