(Bono did use the red teardrops Herdims for a bit. Bono has used the blue too. And also Dunlop red picks with similar Herdim-like grips -- The red Herdims are a little thinner so you might like them better than the blue. Perhaps buy a dozen of each and go from there?)
These are available at the following sites/dealers
http://www.hobgoblin-usa.com/local/contfram.htm
http://www.prussiavalley.com/Other_Accessories.htm

Also, seems that Edge had some Herdim-like picks made to also use.
