We have a regular phone line and DSL for out internet service, and I am considering setting up a VIOP service to handle our infrequent faxing needs. I know Vonage has plans, but they tend to be on the order of 20 bucks a month or so. I am looking for something super cheap so I can hook it up to my fax once or twice a week and send/receive faxes.
Anything out there like that?
Have you looked at efax.com? It allows you to send and receive your faxes over the internet from your computer. I am pretty sure they are not the only such service.
I have looked at a lot of fax services, most of them run about 10 bucks per month. I’m even cheaper than that 
efax seems to have a free option if you are receiving very few faxes. The free service does not seem to help much for sending faxes.
I use uFax for a whopping six bucks a month. It’s rad.
I use Faxaway which costs $1/month. You can receive as many faxes as you like for no additional charge. They do charge for sending, but it is very reasonable. Faxing one page to anywhere in the US is typically $0.15.
And those are probably your best options. Fax is problematic for VoIP providers. Voice is an analog waveform that can be compressed digitally for transmission, and then rendered back to an analog waveform that is “close enough”, to the human ear at least, to the original.
Facsimiles are digital representations that are converted to analog waveforms by modems for transmission across the telephone network. Digitally compressing these analog waves doesn’t work out so well.
There are technical solutions for this, and that involves using VoIP protocols that don’t compress the analog signal. A side effect is that fax over VoIP takes more bandwidth than a standard phone line. In other words, voice is economical over VoIP, fax is not.