It's a semi final at the end of the day, two games away from the final in total. 
You can't force people to buy tickets and watch Rovers. The club shouldn't feel the need to put buses on for people from Blackpool, Shilito said that I think. 
The club have done what they have, cheap tickets for a semi final IMO Rovers can't do much more than that. 
Remember, it was only Xmas a few weeks ago, schools are back, it's a midweek  game and it's televised.