Does anyone have a really good yellow cake recipe for a 12x18 cake that is moist but affordable to make?
I would also need the same recipe for a standard sized cake please.

CC member contributed scratch cake recipes:

http://cakecentral.com/cake-decorating-ftopicp-4528103.html#4528103

WASC cake recipes:
(Can use any flavor cake mix, extracts.)

http://www.recipezaar.com/White-Almond-Sour-Cream-Wedding-Cake-69630

http://www.recipezaar.com/Kakeladis-Original-Wasc-White-Almond-Sour-Cream-Cake-309528

HTH

If you search "yellow" in the recipe tab, there are over 300 recipes that involve yellow cake. That would be a great place to start.

I went to google and entered "yellow cake recipe" .... got lots of great credible sites with yellow cake recipes.