Per Fannie Mae guidelines, a Section 8 voucher is an acceptable source of qualifying income. There must be a history of receiving the voucher before applying for a mortgage and must continue for a minimum of at least 3 years.
Irvine is a pricey area, as Kawain previously mentioned. Your best course of action is to get a complete preapproval so you know what you can actually qualify to purchase. For the preapproval, you need to provide all your income and asset information to the lender. They will pull your credit and run the loan application through one of the software programs to issue a formal approval. At that point, you are good to go!
Good Luck and if you have any other questions, feel free to contact me.