do not buy the IR extender ET-TRM110, it is pure scam.
you will pay 200$ for absolutely nothing else than a piece of plastic and 5 led soldered on a little print + a minijack socket (total value, probably less than 10 buck)
ok i update this post with the technical info.
the five leds are 850 nm as specified in the ET-TRM110 manual. Leds are connected in series
the projector plug delivers 100mA (specified in projector manual) , so if you build your own emmitter make sure you do not go over 100ma, most led being between 20 and 50mA
if the connector drives the leds at 12V, you can expect that each led must have a forward voltage of 12/5= 2.4V, most common led are usually 1.4-1.6V, some are 1.6-2.0V,
so we can say if you take any cheap led on ebay there are chance they do not fit. Make sure the forward voltage is 2.3 or 2.4 V or use a resistor to lower voltage.
The Osram SFH4350 is rated 1.5-2.4V and 100mA with an angle of 26 degree (do not take the the 4550, the angle is 6 degree only ) so it is a perfect match, but you will not be able to fill the missing led with it, because you would then reach 200ma.
that could possibly burn the output port on the projector.
If you need more power It is better in that case to build a second emitter with 5 more leds and use the 2nd output port on the projector.
you can find the leds here http://www.led-eshop.de
If you make your own, there is no need to have a plug at the emitter side, just solder the cable directly to the circuit.
Use a cheap shielded cable (audio grade)
You should be able to buiild an emitter for less than 20$