Are you going to the right section in paypal?
Login to your account
click merchant services
click shipping calculator
You can set up your shipping there.

I set my shipping up as 1 price for however many ordered (1 - 24 pieces)to a single destination. For orders of 25 or more, starts wholesale pricing.
I haven't gotten to many orders for a single unit since then.
I'm averaging 4 per order now.