There seems to be resistance at very low $x,xxx for premium single keyword .tel domains, and even then they can dip down to low $xxx (which was the case with the $200 or so mall.tel auction on Sedo).
Based entirely on that, I have to say like $50 max for this one. Another issue is that about the only thing you can use it for is a directory, and if someone is relying on .tel to get a directory project online then they probably aren't willing to put much money into the project.
In any event, I would probably pay the renewal fee on it when it comes around next spring and hope for directory improvements in 2010. What you are really looking for here is .tel to introduce a Geocities-like template system.