Scopes

glass quality, QA, warranties, illuminated reticles, zero stops, parallax adjustment, weight, length, objective size, tube diameter, lens coating, waterproof/fogproofness, drop durability

What eould be a decent, under $500 red dot that I can slap onto a carbine for home defense (and maybe SHTF) that won't be used past 150 yards? I suppose it doesn't have to be red dot, but ideally I'd like to be able to use it in low light/night time conditions.

Aimpoint PRO would be the best value
Any primary arms red dot
Any holosun red dot
Vortex venom, burris fastfire 3, leupold deltapoint pro. You'll have to buy a mount seperately.