Try Bayou Biolabs (based at Harahan, LA). They offer two scales of
purification - 20 to 40 mg, or 500 to 1000 mg for pUC-based plasmids. I
have not tried this sevice, but their other products seem very good.
You can contact them at bayoubiolabs at earthlink.net
I have not affiliation with this company.
Scottish Agricultural Science Agency.
mulholl at sasa.gov.uk