[tgold]

If racing takes all of your money you're doing it wrong. I've won two championships without breaking the bank. But since I'm not into spending all of my money on racing I primarily race small bikes.
I agree with selling the zx7 and getting a smaller bike. The ZX7 handles like a falling safe compared to the little Ninjas. The ZX is also much more likely to make you pay for mistakes than a more forgiving bike like the 300 Ninja.
I can honestly say these things based on 35 plus years of racing, however I do actually have a fully set up 250 Ninja chassis with a 300 motor that is for sale if you are interested. It's listed in the for sale section here.