Affordable air compressor

Harbor Freight has a lot of really cheap compressors, but their gauges aren't accurate and they bounce when filling. And most are 12v. I don't know of one that wouldn't need a 12v supply (I have several so don't usually think about it). Most "affordable" ones are for vehicles. If they are powered off AC, they usually have a fill tank and are both bigger and more expensive. You don't mention your trade-off preferences.

My favorite, though schrader only is from lowes, the kobalt http://www.lowes.com/pd_292215-40883-292215_0__?storeId=10151&Ntt=292215&UserSearch=292215&productId=3079865&N=0&catalogId=10051&langId=-1 - plugs into the vehicle, but has a removable pressure gauge that can shut off the compressor when at the desired pressure and just displays the pressure as it is filling so I can just attach, press start, then watch until it hits. None of this overfilling (I also have a motorcycle and if you let even a small amount leak it will be under, and leaving it on a few seconds it will be over so it can be tedious to get the desired pressure). Some reliability problems have been reported, but Lowes has been good about exchanges, and this is the one that is actually fastest since it is once on, once off.

" I'd like something AC powered as opposed to running off my car battery."

The 12V ones are cheaper, and can be adapted for 120V AC quite inexpensively:

http://www.google.com/search?aq=f&sourceid=chrome&ie=UTF-8&q=AC+Adapter+For+Car+Charger

I have similar requirements and settled on a 120 volt Campbell Hausfeld Model RP4000 compressor several years ago. It has an analogue gauge which seems to compare well with my separate digital gauge. I use this unit on bicycles, a lawn tractor, our cars, and a horse trailer. This is not a high-volume compressor, so car tires and the like may take a while to fill. On the flip side, some of my bicycle tires run 110 psi and it works fine on them.

You might check out the Porter Cable C2002R, $95. It gets great reviews and the Factory Reconditioned models are recommended for being cheaper and indistinguishable from the regular retail version. I just lost my $55 bicycle pump to a flood and am planning on picking up one of these as a replacement. The smaller pumps seem to have issues pumping up 100-110 psi bicycle tires (in my experience).

I have the Dewalt D55140 and use it for pumping up tires, nail guns, small sprayer. It only has a one gallon tank, but is really quiet so you don't much notice the compressor running to fill the tank. Check it out at amazon.com.

I go with Harbor Freight as well. I am in the aquaculture business and need to move huge amounts of air at relatively low pressure, a killer for piston air compressors. I had a vane compressor ($1200) malfunction 5 years ago and hooked up a Harbor Freight compressor "temporarily". It lasted for over two years. I replaced that with a Sears compressor that I took back after two days. My current Harbor Freight compressor, model #67847, $139 on sale, has been putting out air for over three years, keeping my fish, and me, swimmingly happy.

I have the Black and Decker ASI300. http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=ASI300&x=0&y=0 Has both power options and an automatic shut off. The tire nozzle is very tough, but has some sharp corners so be careful when putting it on in tight spaces.

http://forums.finehomebuilding.com/breaktime/tools-home-building/air-compressor-recommendations