Hi Jerry,
Surprisingly, race tires don't vary much in price with different sizes. Kumhos are typically around $125, and Hoosiers are typically $180.
If the OE tires aren't prohibitively expensive, I would suggest spending several events, maybe a full season, on the stock street tires. You will learn a bunch, and you'll give Randy and others time to determine what sizes and models of race tires will fit.