As LD says bullets are available. I think Knight screwed up on this as they still charge a premium for the bullets or sabots and control the vendors direct sales. I have a .50 and .52 DE's and like them both, however I am moving to shooting conicals in the .52. After this season I will play with differnent bullets, I have about 200 of the grey sabots and my plan is to find a .458 bullet that patterns well in more than one gun. When I am through the grey conicals I expect to shoot lead and maybe paper patch.
When I bought my .52 I paid less than the current deal, having and liking it I don't know if I would do it again.