Internet-wide port scans

Are there somewhat reputable service providers for Internet-wide TCP port scans? What's the typical rate per TCP port? (I'm interested in rather obscure services whose identification may need additional probing, and this data is unlikely on file already.) A full scan needs just 0.5 TB of data per TCP port, so "roll your own" is definitely an option. But I expect that any halfway decent hosting provider will start asking questions after the first billion packets or so, and at least over here, broadband access without abuse management lacks sufficient upload bandwidth, making the results difficult to interpret because the measurements would span several days.