Here's my annual plug. Restaurant.com is a great place to get restaurant gift certificates on the cheap. Generally, they are either $10 or $25 and they're purchased for $3 or $10. If you get on their mailing list, you find out when they're even cheaper. Right now, they're 70% off, only $3 for a $25 gift certificate. I am lucky that there are many restaurants around here participating. Check for your zip code and see for yourself.
The current offer code is CHEERS and you plug it in on the last page. I just bought $45 worth of certificates for under $5.
Be sure to watch for the certificate's stipulations - time of day, day of week, amount spent, etc.