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At least they could have given this poser 8 version to the Pro owners for a very little fee, instead of 129 dollar

129 dollars is well within what I would consider a "a very little fee".
And any actual "pro" work using Poser Pro is going to be able to easily finance the upgrade.
There's a whole lot negative one could say about Poser, but the price has always been very reasonable and well within the affordable range, even for hobbyists. For people using Poser to earn a living, the price is astronomically low, compared to most other 3D packages.