I guess it depends how you look at it. The funds available last season were clearly enough in my opinion. It was not the budget which got in the way. As it turned out a win on the opening day would have got us automatically promoted. Not letting in a number of those last minute goals we conceded would have done the same. Then there was the lack-lustre play-off game. None of these were directly due to the budget but would have all resulted in a much more positive outcome to the season. And I feel the same this season. The budget will be enough if good decisions were/are made and we have some good luck.
But I would that it was the management, not the budget that got us there. Even last season we still had plenty of League One players in our squad, compared to tonnes of Prem players in all the squads around us. Our budget was apparently about 8th/9th, so to expect promotion was a bit unrealistic. We did bloody well to come 4th.