Reported by Joerg Reisenweber, Dec 24, 2013

Order 25 (or similar convenient quantity) per type of 

SML-P12VT(R)
SML-P12UT(R)
SML-P12DT(R)
SML-P12YT(R)
SML-P12MT(R)
SML-P12PT(R)
SMLP13EC8T
SMLP13BC8T
SMCP13WBC8W

http://rohmfs.rohm.com/en/products/databook/datasheet/opto/led/chip_m
ono/sml-p1.pdf

example source SCMP13WBC8W1(white): 
http://www.digikey.com/product-detail/en/SCMP13WBC8W1/846-1111-6-ND/3
973667

Estimated expense: <100EUR