how do i get a copy of an invoice for a part I received

[wooden_flower]

eBay doesn’t create the usual numeric controlled invoice documents.  The best proof of purchase is your order details page - it includes the only unique identifier available, which is your order #.  There is a printer friendly link when you view the order details.

[mega-ma-roo]

Your can go to your Purchase History and select View Order Details. Other than that, you can ask the seller, but I don't know of a way to send an invoice after an order has been paid.