There's not currently a way to have TSM undercut bids, no. It's really a much more complicated issue than you make it seem, and would not be very easy to implement when the majority of players probably wouldn't use it. If you want to do something productive to try and make it a reality instead of whine about it on the forums, there's a website to suggest features for TSM here: suggestions.tradeskillmaster.com
Originally Posted by inseedious
If your campers are using TSM, they are most likely using the Bid Percent settings: http://i.imgur.com/oGHSz1h.png. If you set your bid percent to 95%, and you were posting for 100g buyout, it'd list at a 95g bid. Do the math, figure out their bid percent, and make yours higher.