Can eBay be trusted? I just know that sometimes you get scammed out of stuff so it can be a pain.
Well, when I purchase things on Ebay, first I pay with paypal. That way if I have any sort of problem I can file a dispute with ebay, paypal or both. I've never had to do either, and I'm up to almost 300 transactions now with no major issues at all.
Trick to buying on Ebay, look at the sellers rating. If they have a lot of positive feedback, and very little or no negative, this will generally indicate that they are a reputable seller and one you can feel confident in doing business with - just stick with sellers who have say at least 50+ transactions and most if not all positive feedback and you'll be fine.
Keep in mind though that the really big sellers on Ebay will all have some negative feedback - you can't do thousand and thousands of transactions a month and not get at least a few people who didn't like the product or maybe had an issue with shipping (lord knows the post office has lost more than one of my packages) and sometimes these people will jump the gun and just leave negative feedback without contacting the seller first and trying to work it out.
The one time I did have a shipping issue I contacted the seller, they did an investigation from there end, contacted the shipper, had them locate the package and it did arrive. Granted it was a little overdue, but I didn't blame the seller because they shipped it on time, just that for whatever reason UPS was having an off day I guess and managed to misplace it for a while.
The other thing to be aware of is check the seller's location before you buy. Particularly with aftermarket battery chargers, etc - you'll find a lot of listings and many of them will show you that the seller is located in China. Just be aware that yes, those are usually cheaper, but you are often looking at very long shipping times, sometimes as much as a month depending on how they ship it.
So your best bet is to sort the listings by distance from your zip code - that will put the folks that are selling the item who are closest to you up top, and then just double check to make sure that the person your ordering from is actually a little closer than say China.