The conversion is available, however, as mentioned, its more cost effective to just buy a M9A1. The conversion kit runs from 280 up to 400, and you still have to buy the clips IIRC. I can get a new M9A1 for 400.
Now if you can find a M9A1 that has been damage in the rails or something, that would be the best way to go.. But I have yet to find one that is damaged.