Reading this post and all you guys replacing spindles and starters and all that is no fun. I used to do that years ago.
I've been buying gently used, low hour zero turn mowers, run them for a few years problem free, and then sell it for about what I paid for it. Rince, wash, and repeat. Problem free mowing sure beats having to rebuild decks and replace parts all the time.
My current mower, same as my last mower, is a Toro zero turn. Last one I bought for $1650, ran it for three years, zero problems, just put gas in it, sold it for $2000 last year. Bought a like new one for $1700, will run it for a few years, and sell it. Rince, wash, repeat.
Zero net dollar mowers, with no issues. Its the way to go. Let someone else take the deprecation hit and then buy a low hour unit with under 40 hours (I see them all day long) And then let someone else take the maintenance hit once it gets up there in hours.