Amapi Designer 7 has just been released, and I know Brycetech has done some wonderful things with it for Poser. It is cross-platform, and just under $500.00. Amorphium 3 is also well under $500.00, and I think it is cross-platform. It is a little different, but can be a decent choice for the budget-minded. And then there is the ultimate budget-minded app, Wings3D. It is free, and is a wonderful modeller.