Buying Things From EBay?

Ive never purchased from EBay before but I recently found a shop that has a few things i really like for really cheap. Most are 90%-50% of actual price. The seller has nearly 50k ratings and is almost all 4 stars. Im scared to buy because it is so cheap that I almost feel like there has to be something wrong with the item. Should I trust the seller and all his ratings, or go with my gut and not buy?