Okay, since this is a big topic I thought I would share what I charge for cakes.
I live in Ohio & around me most of the grocery store bakeries charge $15 for a 1/4 sheet & 38 for a full sheet.

These prices do not include fondant"

My round cakes are 2-layers & filled:
8" iced with border& writing $25
8" detailed decoration $30-$35
10" iced with border & writing $30
10" detailed decoration $35-$40

1/4 sheet 1-layer 15 servings $25
1/4 sheet 2-layer 20 servings $30 These prices are for FBCT's, etc
1/2 sheet 1-layer 30 servings $40 I charge more for choc covered
1/2 sheet 2-layer 40 servings $45 strawberries, extensivly detailed
Full sheet 1-layer 60 servings $60 decorations, etc.
Full sheet 2-layer 80 servings $65

9" Cheesecake $30

Wedding Cakes

Buttercream $1.75/slice Extra for fresh flowers, decoration, etc.
Fondant $2.75/slice

Shaped Cakes: I'm going to refer to some in my photos:

Basket Cake with Strawberries(2nd page w/handle) serves 20 $45
Skateboard Cake serves 15 $35
Sesame Street Cupcakes 1 dozen $18
Indian's Jersey serves 15 $30
w/6 cookies $35

I hope this helps at least some of you who need a starting off point on prices.Like I said, these are just the serving sizes that I go by & what my customers are willing to pay for my cakes.

If anyone would like to know how much I charged for any other cake or any other questions feel free to post here & ask.