I like to keep an eye on where the market is for particular machines so I also look each day. Most of my Watch items are auction only and andtan is right, plenty of the auctions do bugger all for a week and then in the final hours and particularly in the final minutes or so they skyrocket.
 I see a lot of the buy it now items without offers at the end of the auction that then get re listed at $250 or so less next time around. So I reckon your "buy it now" with the "offer" option is the way to go, at least you get to say what you want and if it doesn't sell straight up you open up your options with offers.