See VirtualISP at
They are the cheapest I know, as far as startup costs. I just visited their site and can't get through, but was there little more than a week ago. I think they resell for MegaPOP.com.
Similar to VirtualISP was WholesaleISP.net, but they've been bought by CISP.cc this past summer.
I spoke to a rep from CISP at the Fall Internet World Show and from what I understood they are going away from the low-end pricing of WholesaleISP.net and going for a more established clientele - upfront costs starting with a $5,000 setup fee, but then a reasonable monthly charge per dialup user. They may not even be honoring the WholesaleISP.net website prices anymore, I don't know.
Depending on who's package you sign up for and what national network of POPs you use and whether you sign up for phone and/or billing support, prices can range from $8-$13.50 a month or so for each dialup user. Email services and/or personal webspace for dialup users are usually extra.
Currently, I am reselling five dialups to a couple of my clients through a small company in Buffalo named Our Specialties. I purchase the accounts wholesale for $12 each and resell them to my clients for $15.95 as a favor. I provide email to my clients through my own servers. This is a barebones service, but it works. For a limited user base, I can safely recommend Chuck at OSNet. He's really helped me out when there were problems. I know he's got a lot more clients than mine, but I'm not too sure I'd use him for a full rollout of dialup services for your business. You can some limited info at
If you do decide on a company, let me know how you did. I am interested in better solutions.