This system, which you may be able to get for free if you look around
would consist of a MicroVAX-I System with a KA630-AA(?) CPU with 1mb onboard
memory, an RQDX2 controller and an RD31 disk, it will run VMS 4.7 be 
*very* slow and noisy and would need a VT-220 console or equivalent.
Invariably systems that are given away tend to have a higher spec than
this, often a MicroVAX-II CPU with RD54, RQDX3, DEQNA and at least 9mb RAM. 

For this price you should be able to pick up a VAXstation-2000 with at
least 6mb RAM and an internal RD54 running VMS 5.x, maybe a console thrown
in, or if lucky a VR260. Nice machines, but *VERY* slow, the RD series
drives are noisy, slow and unreliable. A typical use would be as an X
terminal over thinwire, as a standalone system OK but fairly obsolete.

For this price, maybe a high end MicroVAX-II system with 16mb and DELQA,
RQDX3 and a couple of RD54's, maybe a TK50 thrown in. But you really
should be looking for a low end VAXstation-3100 for this price. Around
three times the speed (VUPS) and very expandable, quiet and reliable.
Maybe a 3100 base with 8mb and a VR260 and a small SCSI drive with VMS
for $500...

At this level *FORGET* the MicroVAX-II's, the VS-2000's and go for a low
end VS-3100, something basic with DECwindows should be available, maybe if
you are lucky a VS-3100/38 (3.8 VUPS) makes a very nice standalone X box...

As a minimum I would suggest a VS-3100/38 with a VR290 or VR299, 16mb RAM
and a decent size SCSI drive for around $1000, maybe better configured
than this even...

Go buy a new VAXstation  :-) seriously though I would suggest a
decently configured 3100/76 with a VRT19 or a 4000 VLC with a VR299.