you can get standard performance chips from places like Superchip and Diablo, you can also get them to do custom burns-change things like rev limiter, cooling fan temps, etc. You can also get a chip reburned or modified based on tuning needs. If you have an unmodified car, a chip will really make a difference for you.
usually it will depend on what kind of burn you want done. i know FC does it and when i did mine i had the idle raised to 1000 and that was it and it cost $50. usually for a custom burn it will be upwards of $120.