I've had a quick look at the ones I think you're talking about. They contain some pretty standard 'weight loss' ingredients and seem very overpriced for what they are. Things like L Carnitine and Chromium can allegedly help in keeping your blood sugar level so you don't get cravings - but a healthy balanced diet will have the same effect, and they certainly won't make the weight drop off. Many ebayers set up secondary accounts to 'buy' their own items and make outrageous claims. The ones you are looking at are overpriced and won't have any effect on your weight (I believe). If they were that good the government would be charging tax on them and feeding them to the population!
Buying any type of pills over the net can be dangerous, as some are made up in countries which don't control the contents - or, you simply don't get what you think you're buying.
The amphetamine-based ones which were popular in the 70's and 80's, were discontinued here because of people abusing them. They also caused heart problems and other body malfunctions. As the others've said, a controlled diet with exercise, is the best, providing a medical condition hasn't been diagnosed.