I don't ask for their budget but I state what my prices "start" at. If in their description it seems like a small cake then what I say is "I'd be happy to do your cake and I am available for your date. My cakes start at $150.00 and $4.50 per serving. Prices increase from there depending on design and flavors chosen". This way they can determine if you're in their price range.
4/7/13 at 9:53am