I have been shopping on eBay from few years and always found some great deals on most of the products. In fact, if you go to eBay from Microsoft live.com site then you can get some great discount or Cash-back on your purchase. Make sure of doing following things -
1. Register on live.com (register for Cash-back account too). Its free!!
2. Search the product on live.com and follow the link from their site to eBay.
3. If you product is eligible for cashback then it will show a $$ image on the right side on eBay.
4. Make the payment using Paypal. (You can create a PayPal account for free. Its owned by eBay and safe for online transaction.)
5. You should receive your Cash-back within few weeks.
Read more details on eBay Cash-back