I am not making my own, but I have looked in to it quite a bit. If you have the space it can be done relatively easy. The up front costs are going to be installing heaters on your tanks and lines in your vehicle and the cost of the setup to purify the bio (if you plan to use WVO). From what I have read you should expect to pay about .75 per gallon using WVO. There is a lot of information out there on the topic if you google it.