The IM6100 chip may still be available (Electronic Expediters, (818)781-1910
(in North America) listed them at US$23.50 each as of 10/1994), and CESI
may still make their clone, for a high price, but you can't buy a new
DEC PDP-8.  There are quite a few PDP-8 machines to be found in odd
places on the used equipment market.  They were widely incorporated into
products such as computer controlled machine tools, X-ray diffraction
machines, and other industrial and lab equipment.  Many of them were
sold under the EduSystem marketing program to public schools and
universities, and others were used to control laboratory instrumentation.
After about 1976, Reuters bought as many as 10,000 OMNIBUS based
machines per year, with perhaps 2000 per year going to other customers.

Through the 1980's and 1990's, PDP-8 hardware was frequently discarded
or sold for scrap, and many collectors were able to obtain CPU's,
peripherals and occasional complete systems in exchange for the effort
required to haul them away.  This may be changing!  In early 1999, a
PDP-8 system in unknown condition was sold at auction through eBay for
$1526.00; this is far less than the new cost of such a machine, but
far more than the scrap value of such a system!  Owners of original DEC
hardware will likely need maintenance and test supplies.  Douglas
Electronics still makes extender boards and breadboards in DEC format,
see:

  http://www.douglas.com/hardware/pcbs/breadboards/digital.html

As of 2000, there are still a modest number of PDP-8 systems in
production use, mostly PDP-8/A systems.  These are supported by a
shrinking number of commercial suppliers and maintenance contractors.
For example, Michael Coffey <mdynac@netscape.net> has advertised the
availability of spare parts and maintencance documents for Omnibus
systems/

By the year 2000, a number of PDP-8 parts and systems have changed hands
on E-bay.  Sadly, many systems are sold piecemeal, with parts such as
core memory destined to hang on den and office walls.  The market is
spotty, but looking back over the ebay.com sales history is a good way
to get an idea of what parts might be worth.

If you can't get real hardware, you can get emulators.  Over the years,
many PDP-8 emulators have been written; the best of these are
indistinguishable from the real machine from a software prespective,
and on a modern high-speed RISC platform, these frequently outperform
the hardware they are emulating.  An emulator is available from DECUS,
catalog number RB0128; This and other emulators are available from:

  ftp://metalab.unc.edu/pub/academic/computer-science/history/pdp-8/emulators
  ftp://ftp.cs.uiowa.edu/public/jones/pdp8/emulator.txt.Z
  http://www.tiac.net/users/mps/retro/sources/simh25a.zip
  (previously ftp://ftp.digital.com/pub/DEC/sim/sources/sim_2.2d.tar.Z)

The final collection of emulators listed above includes emulators for the
Nova and other DEC machines as well as the IBM 1401.

Bernhard Baehr's emulator for the Apple Mac, complete with an emulated front
panel and a fair amount of software is available from:

  http://home.t-online.de/~bernhard.baehr/pdp8e/pdp8e.html

The Spare Time Gizmos emulator for Windows doesn't have the elaborate
front panel interface, but it appears to be reasonably complete and has a
very realistic teletype interface window.

  http://www.sparetimegizmos.com/Software/WinEight.htm

Finally, you can always build your own.  The textbook "The Art of
Digital Design," second edition, by Franklin Prosser and David Winkel
(Prentice-Hall, 1987, ISBN 0-13-046780-4) uses the design of a PDP-8 as
a running example; development new material based on this book continues,
including an asynch interface chip and, now, several implementations based
on Xilinx FPGAs.  Contact Ingo Cyliax or Caleb Hess (cyliax@cs.indiana.edu
or hess@cs.indiana.edu) for information on the current state of this work.
Other FPGA implementation are being developed by Jon Andrews and David Conroy;
see:

  http://www.jaywalk.co.uk/pdp8
  http://www.jetnet.ab.ca/users/bfranchuk/index.html

"Modern VLSI Design - A system approch" by Wayne Wolf (1994 Prentice-Hall)
also uses the PDP-8 as a data-path example, as does "Verilog Design Computer
Design" by Mark Gordon Arnold (Prentice Hall).

It is worth noting that there are a sufficient number of PDP-8 systems
still operational that some companies still manufacture peripherals.
For example, Storage Computer (http://www.storage.com/) makes RK05
compatable semiconductor "disk drives" that can be directly connected to
the Omnibus RK05 controllers of the PDP-8/E,F,M and A.

Occasionally, someone connects a PDP-8 to the internet.  The most
interesting current venture in that direciton is available at:

  http://www.pdp8.net/

This machine, when working, has complete remote control of the front
panel and even the on-off switch from a Java interface, and there's a
web-cam so you can see the real machine as it responds to the remote
front panel operations.