A good repairer should ask around $40 for inserting a voltage regulator inside the camera (SRTs have plenty of room). That would allow you to use common alkaline batteries without any deviation in results and solve the problem once for all.
As an acceptable (but not totally equivalent) alternative you might try these adapters, they are reasonably cheap:
http://rick_oleson.tripod.com/batt_adapt_us.pdf
The document contains also instructions for doing it by yourself.
Fabrizio