Two things. 1 I have a small dive shop and own Poseidon 135 which is about 4cfm. It is a continuous use compressor I fill my bank of 6 bottles and have never had a problem. Yes it fills slow but I have a beer or 2 while I am waiting. 2 I know nothing of their quality but I just got an email from Alkin they are selling a small compressor for under 4k. alkinusa.com have a look and see if it fits your needs.