I always recommend QuickBooks Merchant Services. Their prices are competitive and you can process everything right in QB. It's a pretty good service. If you want I can sign you up for it and it will be cheaper (I'm certified with QB so I get the fees waived).
Pfax is a good service. It's about $4 a month. I use efax, it's 16.95 a month, but there is more storage and has a few different features that I find it's worth the price difference. Plus, I've had the number for so long now I don't want to change it.