Mechanically, the Snapper RERs are very durable, and time tested.
But they are a breed unto themselves, and as such have a few quirks.
But I own 2 of them. The oldest is a 1968 Snapper Comet RER and the newest is a 1987 Snapper RER.
The '68 model is 7 horsepower and the '87 is a 12 horse power due to me having swapped out the OEM 8 horsepower engine.
Both of these operate and will cut my grass if I need them to.
(but they are not my only mowers).
$300 is just a bit on the high side but these really are good machines.
It is the wrong time of year to be a purchaser of lawn and garden machines, so you might not have much success in bargaining for a lower price.