All the people selling scrap on ebay is almost exclusively do so to scam beginner gold refiners who dont know any
I crunched some numbers and even message a few ebay sellers, most of their responses were complete bullshit. In all honesty ebay only allows it because they get paid.
I'll give you an exact example since I spent a whole night browsing ebay and messaging people just to see their logic, many flat out lied.
So I did some research and old phones (3g and earlier have the most gold). In saying that those models are razr 1st gen, blackberries 1st-3rd gen, and iphone 1st gen. The gold value per phone(and I'm being generous with the estimation) is about $2.50 per phone. Now they are selling lots of these phones, so I looked at a 31 lot of razr 1st gens being sold for $150.
Realistically you need to be able to buy 100's of them for $1 a peice. Now you might say well yeah of course they will sell them for more then scrap price. The kicker is no phone company in the USA, Canada, or the United kingdom will allow you to connect old phones to service, they are essentially paper weights. They tried telling me collectors buy them, ironically I actually work selling collectables and antiques, so no they do not, a collector may buy 1 phone for display, they arent buying lots, so no matter how you look at it, the sellers on Ebay are all foreigners with broken English and they are purposely being deceitful and taking advantage of people. No normal person will buy a phone that cant be connected to service ever. Oh and the cherry on top, they include words like "as-is, not tested, works, and for parts" the first two are to prevent you from getting your money back, "works" is to deceive people who dont know better, and for parts is a joke you cant use old parts in newer phones. I hope this helped. Good luck on your refining.