welcome to the site
at your budget, your asking a lot, on a AS is, problem free machine
as for models, yes and NO
and I say it like this, as the game your playing will come down to what you find in your budget and then based on condition when you go to look at it
what and where you from?
as location can mean a LOT
My advice is this, stay away from atv's with BIG mud tires, and snorkle's
red flags as possible sunk machine or more repairs maybe needed
next will be stay away from E shift bikes, go simple foot shift models
MY model list would be
400-450, older 300's too.
find one low miles and hours in pretty original condition and HOPE It was never sunk!, and cared for
do as much inspection as you can
check wheel bearing,s , take a compression tester if you have one, look closely at color of oil and level, SMELL the dip stick, too, smell for burnt oil, or fuel smells
look at air filter, if its crusty, that says owner didn';t do much for Pm's
but buying used is always a gamble