I think Bangs Laboratories in Indiana have them....
In article <199510100822.EAA152958 at acs3.bu.edu>, yotennis at ACS.BU.EDU says:
>>I am looking for some information oon strepavidin-coated magnetic micro-
>beads used in affinity chromatography or even general information.
>>If you can help , please email to me.
>>Thanks.
>>