"Real" 800 yard rangefinders are tough to get in that price range. $300-350 will get you a Bushnell ARC 1000, or a Leupold RX1000 that will probably max out around 800yard tops.
$200 gets you a 400-600 yard range finder these days. My roughly $200 Leupold RX600 or my dad's Bushnell Scout 1000 (pre ARC model), for examples, will technically range to about 550-600 yards, if the target is a giant reflective metal road sign. However,since I do very little shooting at giant reflective metal road signs, it's more useful to state that they will range to about 450-475yds on a woodline, and around 350 on a deer. Take the great yardage claims for rangefinders with a grain of salt.
Big features on rangefinders these days:
Ballistic trajectory calculator- some use a nice trig function to compute the actual range along the ground to your target rather than LOS, other brands give generic "holdover" amounts based on that function. Read carefully and decide which one you want before you buy. It's very important for bow hunting or shooting from a stand or in the mountains.
Anti-brush features- ranges the furthest target rather than the closest when you're ranging in the woods or an open field. This is really handy.
Reticle- I prefer a nice small one. Critters at 300-500yards tend to get really tiny at 6x. A big giant donut or a crosshair that subtends the target 10 times over is not great,but neither is a reticle so faint you can't range near dusk or dawn.
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