I have just found similar items on Etsy and gone for the 'middle of the road' price. I am only working in PDF at the moment, so my overheads are minimal. I will research printing costs etc later...
With that in mind, my smaller patterns are $3.00, and larger ones are $6.00. I have such a small range at the moment, and am only really finding my feet, I can't tell you if this is appropriate or not....