Depending on the club it's typically around £200 for a 15 minute practice and 15 minute race. Realistically if you genuinely spend £250 a weekend it's probably a bit cheaper than most club racing but there are other forum members who say they spend that much on tires a weekend. Don't forget Becky wanted £20000 to do a 24 hour ProKart race and considered that a normal amount to spend on a few bits of steel box section and a couple of glorified lawn mower engines. Given what other members have said about 2 stroke club racing it seems that spending 10 times the amount you suggested isn't uncommon. Did you take into account tires, engines and routine lifed components in that cost?