Possible to buy this switch for my lawn mower?
Yes. Hit up electronic component suppliers like Mouser or Digi-Key.  They have a staggering catalog of switches and you are likely to find a match.  

Prepare to spend a fair amount of time looking bleary-eyed at the mechanical drawings on data sheets to match the physical size.  

It also helps to limit search to items they actually stock.  If it says 6 week lead time, nope.