Often when the engine starts losing compression one needs to consider the cost of a full rebuild kit which you will need and can be sourced from Mazda or Atkins Rotary - Rx7 | Rx8 | Mazda | Rotary | Engine | Parts. Another thing to consider is the fact that you may have a worn or flaking housing or housings. Those can be sourced from Mazda as well and are around $800 per housing. So like the others are stating, the apex seals are not the only components that will need replacing. It goes with the job that all parts are considered for replacement and all gaskets and seals are a must.