So if your purchase price is $80,000 or more, you'd get the full $8,000.
If your purchase price is under $80,000, you'd receive less than $8,000. For example, if the purchase price was $65,000, you'd receive $6,500.
Hope that helps.
Don has provided you with a clear and correct answer.
To take advantage of the both the CA and FED tax credits a first-time home-buyer must enter into a purchase contract for a principal residence before 5/1/10 (by 4/30/10), and close escrow starting on 5/1/10 and no later than 6/30/10. If this can be done, up to $18,000 in combined tax credits are possible. You can read more about the steps for obtaining these credits via this blog post: http://www.trulia.com/blog/steve_ornellas_mba_re_mastersgri/
If you are interested in the CA tax credit do review the "update notes" at the bottom of the post.