Straight from the ebay news pages;
Bid Assistant manages bids and makes winning the right item at the right price more convenient for buyers.
Bid Assistant places bids for you on a series of items from your Watch list. You tell Bid Assistant which listings you want to bid on, tell it what your maximum bid is and relax while Bid Assistant handles the work of bidding.
Using Bid Assistant, you can group listings together and enter the maximum amount you want to pay. This amount could be the same for each listing, or you could decide to set different amounts based on the item condition for each listing or other considerations.
Listings are sorted by their end time, so when you’ve set up your group, Bid Assistant will bid on the item with the earliest end time first. Our proxy bidding system will automatically update your bid amount up to the maximum amount you set in Bid Assistant.
If you win, you get to celebrate your victory and Bid Assistant won’t bid on any other items in your group. If you lose, Bid Assistant will automatically bid on the second listing in your group for you. This pattern continues until you win one of the listings or all the listings in your group end.
To learn more, visit the Bid Assistant help page.
Could be useful for when there are several sellers offering the item you're after.
We've listed just over a dozen duplicate large or medium studies on eBay. You can see the list on 
