@bronir,
Go to your Purchase History and click on the Order details button. That is as much of an invoice as you will get from ebay. You can also try matching the purchase date with a transaction in your bank account, or credit card statement.
If you need the invoice to fill out a warranty registration card, it may not work. Many manufacturer's will not accept a receipt from an online seller unless they are an authorized dealer of the Mfr.'s products. In my experience authorized sellers have sent me a store receipt, which is accepted for registering a warranty. This is very common with all online purchases from 3rd party retail sites.
"THERE IS NO SUCH THING AS FOOLPROOF, BECAUSE FOOLS ARE SO DARNED INGENIOUS!" (unknown)
