What are your expectations of a compressor -- do you just want it to blow out cracks and crevices or do you want to run tools?
I have a little 3 gallon electric one mounted on my trailer and it serves its purpose -- blowing out cracks, crevices, air vents, etc. If you have a shop, want to run tools, or it will see constant use, you might think about an industrial size (30+ gallon) one. As for the blow nozzles, I have the pen type blower that I got off a Snap-On truck many years ago.
Oh, I got my lil compressor at Harbor Freight for less than 100 bucks.