I do a lot of shopping (read: buying) on ebay - almost exclusively vintage/antique/very scarce items related to my other hobby.
I believe I've posted similar comments here before, but since ebay has come up, I'll address this particular thread as well: your ebay bidding & buying experience is directly related to your strategy which is directly related to how disciplined of a bidder/buyer you are and how badly you've just got to have the item.
Ebay is designed on a timed auction system so you can use the clock to your advantage by entering "snipe" bids in the last possible moments before the clock runs out in hopes that your fellow bidders will not have time to react and bid even higher. This strategy is really only useful when there is a very scarce item listed on ebay in auction format AND you're willing to own it at nearly any cost because there might not ever be another one listed (or perhaps it would take decades for a duplicate to be listed).
I
only snipe manually. I do not rely upon third party apps, websites (free or paid), etc. to win ebay auctions for stuff I
really want to own. If you seriously want to win an ebay auction, you should be on the auction site for the last 5 minutes of the auction ready to bid in the last possible moments. Yes, I've lost a few times (clock ran out), but only because someone else was entering snipe bids for more than I was - no funny business there, they were taking the same risks that I was and they prevailed. IF you want to win ebay auctions with snipe bidding, you have to be prepared to bid crazy high amounts. Of course you have to be willing to actually PAY that much if you win, too, so it's something to keep in check.
You guys will think I'm nuts, but I've even set my alarm clock to get up in the middle of the night to enter my snipe bids for auctions ending at odd hours

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It is, in my opinion, a complete waste to enter any bid on an ebay auction prior to the last possible moments. All you are doing is running up the price and giving other bidders more time to consider what they're willing to spend and more time for them to ultimately outbid you. There are, however, a lot of people that enter their maximum bid very early in the course of an auction and let it ride. This takes some discipline to enter one bid and let it go and also takes the expectation that you will probably NOT win the auction. That said, those kind of bidders do make a great point - they're willing to pay what they're willing to pay (and no more) at any point during the auction. If they win, great. If they don't it's because they bid their maximum and someone else came along willing to pay more.
Buy-It-Now listings are nice - you want it, you pay a set price and the transaction is done. Best Offer can be similar (although you get three tries) - submit what you're willing to pay and the deal wither goes or doesn't.
There are rarely "deals" anymore on ebay. Instead, it is a platform in which things that actually get sold sell for top dollar. Items rarely slip through the cracks without being noticed by many other folks looking for the same item you want.
Re: shipping fees. Ebay is getting a cut of shipping fees these days. Between the shipping cut ebay takes and the other auction fees that need to be paid, sellers get hit with about 10% in fees relative to what their item sells for. That does not include the cost of the listing and any "features" the seller ads (reserve price, etc.) Many sellers are not willing to absorb this, so they offset it by setting higher prices and higher flat shipping rates for their item. Most are not trying to make a profit on shipping - they're trying not to lose money on shipping.
No, the seller's can't see bid amounts and can't directly run the prices up. Shill bidding can still occur, but it's much harder to pull off these days and ebay aggressively targets and penalizes people that engage in that activity. In 99% of cases that is not what's happening - it's other legitimate bidders running up the price. If you carefully check how ebay's bidding works, you can see that it is possible to win by as little as one cent in certain circumstances.
Everyone likes to talk about the evils of ebay, but nobody has a truly comparable alternative. Many have tried, most have failed. The ones that have managed to hang on don't hold a candle to ebay in terms of users and available items.