I can't find an answer for this question so I appologise if it's out there.

I still consider myself a newb and I'm looking for my first stone. I'm looking for a good hone for the money. I'm debating the norton combo 4k/8k or something cheaper. I have a question about the norton combo. I read a great post about properly lapping a stone. That in order for your stone to give you a proper edge you may have to lap up to an 1/8" off of it to get it as smooth as it should be to make the finest edge. Also it seems many of you give your stones a quick lap before each use. I think I read the norton stones are only 2cm thick. If I have to lap a lot off both sides of this stone I may only be left a 1/2" overall. I have reason to believe my beard dulls my razor fairly quickly so I may use this pretty often. I have no idea how long the stone would last and wanted your opinion, since I'm on a budget, If the combo is a good buy compared to single grit.

Thanks in advance!