My 1996 Chevy Lumina slightly overheats...
 

I don't really know much about cars, so the only thing I can say is my lumina's temperature arrow thing goes beyond the middle. Also, my AC is barely getting cold. Maybe those two are separate problems. All the fans still work and stuff, but the AC's air gets hot by the time it reaches my face. It is just slightly cold if I put my hand near the fan.

I'm worried about the overheating mostly. The arrow goes beyond the middle, like maybe 75% towards hot. Is this going to be a cheap fix, or will it be expensive? I got this car last summer for around $800, so I don't really have much money to fix it. The mechanic said to recharge AC it will already be over $100, and that's already kicking my budget, so anything more than that is something I cannot afford. Should I just sell it while I still can? Maybe even for a higher price

I'm a 96 Lumina owner. I would first replace the radiator cap. It couldn't hurt. Then check the temperature. You didn't mention your coolant level but it may need to be flushed and bled. Seems like you thermostat is working but it could be stuck. The thermostat is a mother to replace. I'm not a mechanic so I don't know how recharging the AC affects your heat. Although you could have a clogged heater core. This should be enough info to continue your research.