Check Engine Light 2000 Accord LX

Hello. Recently while driving my check engine light came on in my
Accord. The car was running fine on the freeway until I stopped when
getting off, at the off ramp. I noticed the car was idling a bit low,
around 500-600 RPMs. This had happened to me before and I believe I
just added some fuel injector cleaner to the gas tank and it cleared
up this issue. I tried this method again and after half a gas tank
with the cleaner it has gotten a bit better but the light is still on.
I tried to take the car to Autozone to get the code read but
apparently they no longer do it for free and neither does Pepboys. I
was wondering what is the cheapest, reliable OBD II reader I can buy?
or if you guys may be able to help with that the problem may be.

I'm not much of a car expert. Recently my brother gave my car a tune
up, replacing the spark plugs, wires, and cap. One thing I do remember
that may be an issue is that I had to drive pretty much close to empty
on gas on a long stretch of highway recently, could that have affected
anything with the dirt and misc stuff at the bottom of a gas tank?

Any help would be appreciated guys, thank you.