In the end mate I needed no parts from italy, just some stuff from the auto electrician. Its possible you have the same problem as me. My symptoms were similar in that it was an intermittent problem that seemed to sollve itself after a break (but sometimes not).
You can test various parts of the system with some heavy cable. If you have a multimeter its even better.
I'm no auto electrician, but I'll run you through some tests to try to diagnose the problem. I'm assuming the setup is the same on the s2r as the m900.
These are not really steps. This is to be carried out when the bike isn't starting.
1. with the ignition off, run your cable from 1 and touch it on 5. This should turn the starter. (If not I guess you have an earth fault or a problem with the starter motor terminal or the motor itself, but this doesn't sound like the case).
2. Leave one end of the cable on 1 and run it to 4. This should start it also. If not you have a problem with the lead from 4-5.
3. Leave one end of the cable on 1 and run it to 3. Turn on the ignition and hit the starter. If it turns you have a problem between 1 and 3, if not, the solenoid could be at fault. Check the lead from the starter switch is plugged into the solenoid between the terminals.
3.1 If you suspect the solenoid, cable between 3 and 4. If it turns the soleniod is at fault.
4. If you have narrowed it down to a bit of wiring you can check each section with the multimeter. Check the resistance from one end to the other. Infinite resistance means a break somewhere.
I did this and ended up narrowing it down to the connector. To test the connector poke your multimeter probes into the wiring at 2, and on the lead on the other side of the connector. Hope this helps
Norm I used one side of a bit of white household electrical wire stuff (my sparky bro calls it 'twin').