I don’t use one but…have you checked out Kensington Microsaver products? I think they’re regular lock is $56.95 MSRP. You can probably find it online but something closer to the price you want.
I’m sure it can stop the opportunist thief that is just passing by but I am sure if someone really wants your TR this will only temporarily stop them from taking it. That is why I lock up my office at work as well as put my TR in a locked desk drawer if I am going to be away from it for some time.