I ordered 50 KSC1845s from Mouser on November 8, the current delivery date is now February 12 after being knocked back three times...
I'd go for the RS stock, but they don't ship to the US (they redirect to Think Allied, which has none). However, for $40 you can currently get 50 2sc1845s from B+D Enterprises, although this sucks compared to Digikey's price of $75 for 2,000 KSC1845s when they are in stock. Express Technology Group and 4StarElectronics both advertise available stock, but has anyone ever used them? Doesn't seem like they are geared toward the hobbyist because they want you to request a quote.
I will look into the KSC1815s (lower voltage KSC1845, right?), but will have to check that they are compatible in all the places I need them. Off hand, does anyone know of typical places where the KSC1815s wont cut the mustard? (e.g., locations in a Pioneer SX 828 or Yamaha CR 1020) Obviously, I can sift through the circuit diagrams if necessary...