This quote hits close to home and may just be where you need to concentrate. The stores will sell you up to 24mg/ml of a juice that you like. So, take that and dilute it x2 with a VG and you have twice as much that is 12mg/ml! That will automatically give you half the cost of the juice.
For coils, use rayon or good cotton. Read up on tensioned coils and you may have a better experience with them. The tensioned coils anneal better and give nice results.
I do like the poster who buys them by the 100's! What a deal that is.
I do that for my wife. I buy her favorite flavor a 2X the nic level and cut it by 50% with VG. Cuts the cost in half.