Usually less than $100 a month. I buy and sell audio gear to finance this hobby, last month was a good month. With $1000 play money it was easy to spend it on this hobby... new radio, Picco engine, tires and rims, etc. I probably spent $500 alone on my Savage. It's not a cheap hobby but I try to keep my 4 cars and my son's 3 cars running by wheeling/dealing and side work. I never take from savings or use a credit card and I could just as easily spend $100 a weekend at a bar, but I don't. In fact my only vices are this hobby and 1:1 size cars.