Went back to Target after dinner and got the $40 RCA ones. Effectively the same thing and even same brand as Radio Shack had for $50 and Best Buy had for $70, if not necessarily exactly the same model.
Since all my home wireless networking and cordless phone stuff is in different frequency ranges, I'm not worried about any interference with the 900 MHz headphones.
They work great!
Rest of the evening will be relaxing TiVo catching-up, then a good night's sleep.