People selling items on eBay cannot add feedback about themselvs although they can have a friend do it but that dosen't work so well as the feedback would be from the same people all the time. Each bidder and seller has a unique name just like on emails.
I have personaly bought and sold many items on eBay , the big draw back is you do not get to see the item and unless it is new (and even then it might not be new) You have no gaurentee it will work or is the correct item. You are stuck with checking the seller's feedback to see if people that bought from them were satisfied with both the shipping arrangements or the item. I have made some great deals on a lot of different items and there is a lot to be said. One thing to be aware of is check the shipping costs and add thet to what your final bid is........... is it cheaper than you can buy the item localy ? also you are stuck with the mail or emails to resolve problems along with the seller's honesty. I have been very lucky so far and in selling over 300 items I have refunded money to two people (including shipping due to the item not being what they expected or in one case I did not describe the part in question and it turned out it was for a different year and model.) When selling I usualy accept Money Orders or Cashier's checck and if I take a personal check I wait until the check clears before I ship. When you list something , box it up and get it weighed first and then it can be checked for charges on shipping with the US Postal Service web site. (Remember they bump it up to the next pound so if you have a 3 pound 10 oz. package it will cost what a 4 pound package would)
Don't get carried away bidding like people do at auctions and I wait until the last minute to 30 seconds to bid, that way I don't run the price up and bid what you are willing to pay. You might find an item that is sitting at say 30.00 and you are willing to pay as much as 50.00 , bid 50.01 at the last minute that way if it is wanted by someone else, they won't bid it up to 36.00 and get it. Your bid will only go up by an amount slightly higher than the next higest bid like 37.00 in that case even if you bid 50.00
Most people dealing on eBay are honest and I am sure it is the same for most auction items offered by the other set ups like eBay.
Hope you find stuff you need and get a good deal on them.
Dennis