If you wanted to, you could end the listing and sell to the current bidder at the current price, as long as you were happy to only get the current price. If it's the current bidder and they offered a higher, acceptable price, you can also cancel their bid, end the listing and relist as a Buy It Now for them - that's all ok to do by eBay, as long as you're willing to accept the price they've offered and are ok with not letting the auction run its course.