I'm having trouble determining how much I paid in total for playoffs last year, but it feels like the increase was a big one. My first round tickets went from $115 each to $130, the second round from $156 to $175 and the third round from $203/ticket to $245. Ouch. If we make it to the finals, my tix are $365 each.
For those who don't know, with playoff tickets, you pay for the whole thing up front, under the assumption that they will play four games in every round for four rounds (i.e., you're buying tickets for 16 games) and they reimburse you the difference when the playoffs are over.
For those who just want to attend a few games each year and don't care who you see, there are always same-day tickets available on the Celtics resale site below cost on game-day for the Phoenixes of the world.