Well, that is a personal choice. I would go compare the 2. The modeling is better in pro, but you can buy hex, which I did even tho I have pro.The file support and animation tools are the other big areas...like with mocap data, graph editor.C5 standard is even better than C4Pro except for file support and the 2 included plugins (cadstyle/transposer). So for that you can't loose. Just make sure you aren't missing something you will want later because it will cost the same price to go from c5 to pro as c3 to pro. I doubt I will use every pro feature, but there was enough there that I decided to get on the pro side now for later upgrades.Matchmoving I think is only in pro, as well.

No need to think outside the box....
    Just make it invisible.