At the end of the day Pinball Resource have made the decision that they have enough business without the worry of PayPal and all the problems it brings - good on them I say.
They have parts that people want and if you want them you have to play by their rules.
Notice how you can't pay your rates/car rego/fines/insurance bills/electricity/gas/petrol/car finance payment etc etc etc etc using PayPal - why do you think that is?????????