Buttonwillow is not a track that is extremely hard on the tires. Especially since it sounds like this will be your first track experience, I highly doubt that you will get anywhere near the limits of your current stock setup. Just make sure you have your pressures set properly. At the track, focus more on being smooth rather than being fast. The smoother you are, the faster you will eventually go.
In regards to "Racing Tires", this is usually in regards to R-Compounds or dedicated slicks, neither of which you need to worry about at this stage. It's much better to learn vehicle dynamics on street tires as it is much easier to recognize the limits as they are approached. Certain R-Compound tires will just breakaway from you unexpectedly with very little to no warning.
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Now if you really insist on having a separate track setup, our 18" VMR VB3 wheels would make an excellent option. Paired with a set of Kumho MX's, you'll have great street/track setup for < $1500