Hi Kai,
I have already got quotations from RS for several +5V I/P +12V & -12V outputs including one TRACO make convertor. Here is the list of prices quotated by R.S.

S.NO  RS STOCK  DESCRIPTION         S.S.M.        UNIT PRICE
      NO.                                         ( in Rs. )
------------------------------------------------------------
  1.  0592442   NMA 0512 D            1              1043.00
  2.  0592470   NMA 0512 S            1               991.00
  3.  1301304   NMV0512 S DC-DC       1              1241.00
  4.  1563574   TEM2-0521 DC-DC       1              1901.00
  5.  1916568   DC-DC TMA 0512D       1              1080.00
------------------------------------------------------------

All these covnertor's costs in US$ is from 21USD to 40USD.I don't know why R.S. prices are so high here in INDIA. Might be a regional issue.

Regards,
Prahlad Purohit