Hi guys, yep I had noticed these t-shirts too and had been rather tempted but like others, I felt they were a bit expensive and I wasn;t sure what the quality would be like.
I am guessing they are not licensed by IMPS but do look like they are at least being made by a known company rather than just being printed up cheaply by someone at home. I do like the "weathered" look to the print which indiates to me they are probably quite good quality as this seems to be quite popular at the moment.
Please remember though, it is just as easy to get your own t-shirts or hoodies printed up with the many online companies doing this. I was reall impressed by the quality of my hoodie last year and still love it after it has been worn and washed a LOT!
Here is the company that used:
http://www.tshirtstudio.com/