TruGlo makes one with a 2x magnification I believe. Most don't magnify at all. Yes....."the affordable ones" should be good enough for general use on almost anything. I have an "affordable" BSA Red Dot for my AR-15 carry handle mount. Works fine and lasted for several years. Again....the "affordable ones" do require batteries. The model I have comes two ways...the dial or push button brightness settings. Red Dot sights are not scopes. The dot is illuminated and bounced off a mirror to appear unobstructed in the view in the center of the glass. Some of these optics also offer different reticle patterns or different colors. In my opinion, Red Dot sights shouldn't magnify to be used as intended.
Mine uses relatively common 'coin' lithium batteries like the CR2032 I think.
BSA Optics - Illuminated Sights