Powerslam ran tape trading adverts going back to at least 1994, although Rob Butcher was the primary trader in those days and the fact that he was second in command to Fin Martin probably helped.
Powerslam definitely ran tape-trading adverts because that's how I got into trading in 1999 (there were two features on All Japan in the spring; one on Baba and then on Vader). We got our first internet connection around the same time, too, shortly after Owen died I think (which might've helped my pestering).
I can clearly remember finding issue 1 of Powerslam in a newsagents when I was on holiday with my parents (its predecessor Superstars of Wrestling stopped being sold in the area where I lived around issue 11 or 12, and with the relaunch, Powerslam received a greater distribution through the UK). After buying it I realised that it used to be SOW and they were selling back issues of that magazine. Purchased about half a dozen and there was a two page write up on ECW The Night the Line was Crossed and the magazine wrote it up like it was one of the greatest shows ever and a must see event. In the readers pages there was a plug from Rob Butcher advertising what tapes he had and this was one of them. Although a bit wary, considering he wrote for PS I thought if he was to rip me off I would complain and bitch to the magazine and Fin Martin (ludicrous in hindsight as Rob was a tremendous guy). Sent off for his catalogue and that was the start of my days in the Tape Trading community, although I was just a buyer until the DVD days when I got into it pretty heavily. There was a story on a UK forum about how Rob bought and paid off his own home from his time as a tape trader/seller (can't remember exactly when he called it quits as I was away at Uni at the time) until selling all his stock, videos, converters etc to GWI.