The GP's and the SWEFTA shoots will rack up 6500 miles for me this year. That's about £650. You can't even buy a decent gun for that! Bargain.
Step 1 Buy an old diesel (Pre 2000 and no turbo)
Step 2 Buy a load of new, clean veg oil from the wholesalers
Step 3 Pour it in the tank & drive to the shoot