The clean one actually wasn't THAT difficult to find here... It shipped a few times anyway, and I saw it in a few stores. The dirty one was very easy to find though. As easy to find as the Bespin Guard at one point actually.
I'm still disappointed with this figure, and hope they make a new one that's more poseable some day.
If you're wanting an army of them (clean) and an army that arguably looks BETTER than the POTJ version, might I suggest buying up loose vintage ones, and give them your own (more detailed) paint job.
The vintage figure is surprisingly accurate in sculpt, and his pose is much more "neutral" and acheives the attention pose needed for an Emperor's arrival diorama. They're relatively cheap too, especially if you find a few in a box that are in sort of beat up shape.
The helmet's actually more properly scaled even, as the POTJ figure's helmet is a tad small. I've seen some customs using the vintage figure that really REALLY look impressive.