Been looking for one for Xmas pressy (for me

)
What's the differance between electric and petrol powered compressors? As in power out put, reliability?
Not going to be using it flat out everyday, just for ease of use on my car etc
Are the package ones off eBay any good?
What sort of power/litre should I be looking for?
Don't want to end up buying a crappy non powered one!
Any info gratefully received cheers