You can kind of feel if the machine is quality. It might seem way too light, or it may bend when you twist the plastic case. From what I understand, manufacturers will make machines that aren't so great for mass market (Wal-Mart) and make quality machines for dealers. The in-between seems to be ebay. You can get dealer machines on ebay for the price of mass-market machines. Often, legit dealers will sell their items for less on ebay, even though they are new and come with the same warranty.
A better idea might be to visit your local dealers and see if they have any trade-in machines they are selling for less, especially if they will stand by the sale and offer support.