Adding Best Offer to eBay Store Items

I sell a lot of stuff on eBay, mostly with the auction format, but also many fixed-price store items.
I've decided that I'm going to begin offering a "Best Offer" option on my store listings to see if that can't generate some extra sales.
For example, a watch like the Oliver 44 Tractor Watch pictured here will have a store price of $19.00 and also a Best Offer option which will automatically accept offers above a number set by me. (just between you and me that number is $12. shhh.)
Personally I think the watch is worth the full $19, but if I can pick up an extra sale or two and still make money, well, in these tight times I've got to give that a go.