well, for me modeling was something that took a while before it finally took hold...probably because i am a recreational user. ta-dah!  those are the drums behind lame jokes if all you wanted to do was make clothing then you could get away with using some of the above mentioned. however, i am reading your post differently and am assuming that you will want to do more so you are looking at some of the programs markschum mentioned and then you have maya, max and don't forget z-brush! yes, they all have free 30 day trials! good-luck being able to learn anything more than creating a sphere within that time frame...unless you've had previous experience with 3d modeling. the concepts aren't difficult it's just learning how to make the program do what you want it to.

as to which one? the ones i mentioned are the 3 biggies right now and i believe they all have some student discounts available...but don't quote me on that. max and maya are basically the same and you continue to hear good things about z-brush who's been around for a while now. you can't go wrong with any of them though max and maya will probably give you the most control and flexability. new version of max is due soon here i thinks.

Comitted to excellence through art.