You can get 8% cash back on eBay Buy-It-Now purchases from Microsoft by using their Bing search engine.
1. Sign up for a Bing Cashback account (it’s free, only Windows Live and PayPal accounts are required).
2. Perform a search of what you are looking to buy using the bing.com search engine.
3. If there isn’t an eBay link at the top of the page, do another search for something more common or generic (like iPod, Xbox, etc).
4. Click the eBay link in the tan box to perform the search again at eBay.
5. After arriving at the eBay site, you can search again for the item you are looking for.
6. Buy an item using Buy-It-Now, and pay for the purchase using PayPal.
7. On the page that confirms your auction has been paid for there will be a link to claim your cash back. Click that link and log in to your Cashback account.
8. The credit will not show up in your account immediately; it will take a few minutes.
9. Funds will be available in your Cashback account in about 60 days, at this point they can be transferred to your PayPal account.
I just bought a projector lens this way, and sure enough, 8% of the purchase price showed up in my Cashback account. Pretty easy way to save.
There are restrictions that apply. You should probably click the cashback link on the eBay site and read over them there.