There are other brands which work for booting as well,
such as the Toshiba
XM-5401B, XM-5701, etc which are probably less expensive than the DEC
branded ones and work effectively the same.
I've gotten XM-5401B's for $5 apeice from a PC scrapper before, they're what
is in my Alpha Workstations. What gets me is a RRD42 seems to cost as much
as a brand new PC CD-ROM!
Zane