Curtis Novak has started making a variety of Bi-Sonic/Darkstar replacement pickups:
http://curtisnovak.com/pickups/BS-DS.shtml (http://curtisnovak.com/pickups/BS-DS.shtml%20target=_blank)
I haven't had a chance to try them and haven't heard of anyone yet that has, but I am very tempted to get a pair for my Guild M-85 II. They are pretty expensive though...
HI Harry,
Thanks for the information. Just last week a pair of Dark Stars sold for slightly over $700.00 on ebay.