Good point(s)
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You have yet to tell us why you made the purchase outside of Ebay
I do not understand what the confusion is about purchasing "outside of ebay." Over many years I have purchased from people who had something for sale that never was listed on ebay. I also have purchased things from people whose items did not sell on eBay, and I made them an offer after the auction ended and they accepted. I have NEVER had anyone do this sort of thing before.
I bought and sold on ebay before PayPal and photos. In those days you had to send a cheque or money order. I never had any problems buying or selling. Ebay simply changed a lot after it was sold and went public.
Ebay is not necessarily a guarantee of anything, either. I purchased one rather expensive item on ebay a few years ago but could not get the payment to go through because at the time, PayPal said I had reached my "sending limit." PayPal no longer has "sending limits," but at that time they did. The seller had at least 2000 good feedbacks, so based on his long standing as a good seller on ebay, I sent him a personal cheque.
He shipped the item without proper packing, and it broke in transit. FedEx denied the claim because it had not been packed properly for shipping. He never refunded me. So, there was an instance where I went through ebay, paid by cheque because of PayPal's "sending limit," and lost my money due to an unscrupulous seller. Ebay saw the emails between the seller and I but refused to do anything. Plus, they continued to allow him to sell on ebay.