Chris, I'll start by saying, it’s down to you to do the research and put together some kind of business plan. Nobody is going to hand you a ready-made-business on a plate; it just doesn't work like that. However, luckily you found this forum, there's a wealth of knowledge and inspiration right here – which should help you to get off to a good start.
As you want to sell on eBay, choosing the right product is imperative. It’s often really hard to break into certain markets, so look for one which isn’t infested with other businesses. It’s also fundamental to have your own business model, rather than trying to duplicate what others have already done.
I’ll tell you about a friend of mine, he started selling on eBay about three years ago, after being made redundant. Like you, he was stuck for a product to sell. He dabbled in different markets for a while but found nothing worthwhile. He eventually decided to look for something which was eco-friendly, as this was something heavily featured in the media and therefore people were looking for a way to do their bit. He found a factory in China and imported low voltage light bulbs. After investing just a few hundred pounds he doubled his money. He continued to sell low voltage bulbs, in various sizes and styles. He then started to bring in a number of eco-friendly products (remote sockets, wind-up torches, recycling bins, etc. etc.). He has since had is own packaging designed for all of his products, which is completely biodegradable. It’s not the most exciting idea, but it’s made him a very wealthy man.
My point is, there’s money to be made selling on eBay, you just need to come up with something unique and stick at it. Don’t expect everything to happen over night, it takes months/ years to build a productive business.
I wish you the best of luck with your venture.