Hello AdamD. There are several points to consider when bidding on eBay:
1. If you see a plant you want to acquire, figure out how much you really want to own it and establish your maximum bid. Do this a couple of days before the auction ends. Put a "watch" on your target. But do not bid.
2. Make sure you have a good and fast Internet connection on your computer.
3. Approximately a minute before the auction ends, enter your maximum bid. Most people enter round numbers. But you apparently had an odd number on your bid, such as, $34.57--and that is why you won your bid. Entering an odd number like this will increase your chances of winning an auction.
4. This is why you need to know how fast your internet connection is--confirm your bid T-5 seconds. This is known as "snipping". Doing this late bidding gets your adrenaline going but increases your chances of winning.
5. If you loose the auction, chances are the vendor will have another plant available and you'll see it up for auction. I'm very cynical when a vendor puts the word "rare" on their plant's description.
I hope this helps. eBay has gone to great lengths to protect its bidders' identity--no one but you knows your maximum bid. If you were bidding on a particularly popular item, at the end of the auction, you can see how the bidding transpired through time. This is a good way to determine how late you can go before you hit "confirm bid".