I finally found a PS pump for $165 from "Bill's Used Mercedes Parts"
http://www.mercedespartsused.com/
866-228-7580
The Vickers "126 460 3580" is the same pump as a "126 460 2280".
The rebuild kit was $6 + shipping.
The Mercedes dealer wanted $536.64 for a rebuilt one and $846
for a new one. Buds Benz wanted $295 for a rebuilt one.
http://mppumps.com wants $140 + $200 core, but mine is broken so no core.
Just for comparison, my friend bought a used 50K mile engine and transmission for his Toyota corolla for $750.