The Tigers expect to take 1,000 supporters to the AJ Bell Stadium and have offered free transport for the first 700 who buy tickets, most of which have been snapped up.
The move comes after a crowd of just 5,627 - just over half of Warrington's average attendance - watched Powell's men win at the Halliwell Jones Stadium last Thursday.
"It signifies how close the club is and how much the supporters mean to us," Powell said.
"We know what it feels like when they are behind us, they are pretty vocal.
"For the players to do that, it's an awesome gesture and absolutely the coaching staff have chipped in.
"It can be quite empty that stadium. It needs to feel like a play-off game and I think our fans will really help to do that.
"Salford were really well supported last week at Wigan and they will see it as a massive opportunity to knock us off.
"We had an awesome following at Wigan last year and we couldn't quite convert that opportunity to get to the Grand Final.
"This year we hope we can. We're in a great place."
Castleford forward Oliver Holmes says the initiative arose from a Whats App chat among the club's senior players.
"It got thrown into one of the leadership group chats and everybody jumped on board," he said.
"It stemmed from seeing the amount of fans that went over to Warrington which is no easy job on the M62 on a Thursday night.
"It made a difference for us and we want that again at Salford. It's not cheap so we thought we'd chuck a bit of cash in ourselves and give a bit back to the fans."
Powell hopes to have back-rower Nathan Massey back for Thursday's knockout game after missing the 14-12 win over Warrington with a shoulder injury.
Meanwhile, Powell played down increasing speculation over the future of England half-back Luke Gale.
Although he is contracted to Castleford for another two years, Gale is expected to join Leeds for 2020, with St Helens scrum-half Danny Richardson set to replace him at the Jungle.
"Luke Gale is contracted to us next year and, at this moment in time, that's the way it will remain," Powell said at his weekly press conference.
