Android: One of the best ways to find great deals on eBay is via auctions that have misspelled words. An "Xbox Connect" will often sell for less than an "Xbox Kinect" since fewer people search for the wrong version. Eaby makes it easy to find such items on Android.
The app is similar to the previously mentioned FatFingers. You can search for any item, choose which country's eBay store you want to look in, and even specify the categories you're interested in. Hit Search and Eaby will take care of the rest, giving you the best results along with options to sort them.
Eaby also has a Pro account that lets you get rid of the ads at the bottom of the page and save searches for a quick lookup in the future. It's neat, but perhaps not worth the $US1.50 it asks for. Take the free app for a spin and only buy if you think you need that feature.