I'd use another worksheet.

I'd put the valid sizes in column A (A1:A###)
And put the prices in column B (B1:B###)

Then use data|Validation to choose the size.
See Debra Dalgleish's site for some nice notes:
http://contextures.com/xlDataVal01.html

Then in the adjacent cell, I'd use =vlookup() to return the price for that size.

Say the cell with the size is B2, then in C2:
=if(b2="","",vlookup(b2,sheet2!a:b,2,false))

Debra has some notes for this function, too:
http://contextures.com/xlFunctions02.html

lindsielynette wrote:

I'm working on creating a sales order document for photography. I want to be
able to have a column that automatically picks a price based on the dimension
of the print choosen. (i.e. 4 x 6 = 1.50, 5 x 7 = 2.00) That way clients
only pick the dimensions, but don't have to pick the price too.

--

Dave Peterson