Completely the right plan, I agree. If you want to get a substantial stake you really do need to look for the best possible cost since it still currently requires a lot of money to get a big holding. I managed to get a lot of my holding before march, although my cost base is not quite so good now with recent buys! If it does go lower (and the general market looks quite likely to be in a downtrend), it's a great opportunity to take your time and be patient to get the best deal.
And I agree, the growing user base is key reason I'm investing. Not quite so sure about the whole economics of the stystem, but I'm pretty committed now! ;)