My personal business practice in selling parts is i keep the shipping costs separate from the price of the part that i'm selling it at.
Part is a separate cost, and the shipping is another separate cost.
That may be just me, but it's the way that i do my business. Personal preference, i guess.
And ya, shipping costs have killed a lot of my sales, as i routinely sell rebuilt suspension, and brake parts, when packaged up, weigh in at quite a bit of pounds.
Living in California, on the west coast, and shipping parts to east coast states, from Maine, to Florida, some people just don't want to pay what it costs to get parts from point A, to point B, in this day and age.
And lots are still just clueless how much shipping costs these days are by the mailman, UPS, FEDEX.
Then on the other hand, sometimes i can't buy parts, knowing how expensive it would be for me to get them.
Something to buy, rebuild, shipping costs, just doesn't make it profitable from the get go, to make it worth while, with little to no profit margin.
So i gotta find, buy, parts pretty much locally, before i can invest my labor time, in doing what i do, with parts.
As far as Pay Pal goes, i always give the buyer the option in paying me thru Friends or Family, or Goods and Services.
I calculate both figures for them, when giving them a quote.
Then it's their decision on how they want to put the payment into my Pay Pal account.