I had a look on bike bandit and have come up with this:
RM250
03-07 - 2516386-001
02 - 1096960-001
01 - 489900-001
00 - 4181-001
96-99 -1478133-001
94-95 - 489883-001
RM125
04-07 - 3634272-001
01-07 - 2516385-001
1478132-001 (longer?)
489896-001 (rubber tip)
00 - 3539-001
98-99 - 3538-001
94-97 - 3829-001
For the 2004+ RM125, there are 3 different pictures of levers, and 4 different part numbers. They all share the same rubber tip lever, and 1 other lever, however it looks like there may be a longer one, however it is hard to tell by looking at the picture. So it looks like a genuine lever for a 03-07 RM250 is the go.