i have eight Platinum But it's best to have the latest with platinum though it's easier but it has more benefits than the older versions

For only 30 dollars more, Vegas Movie Studio HD platinum 11 production suite is fantastic. It's the same software as the 100 dollar version, it just includes an audio program, and dvd architect, which can help in the future. I recommend it. I got mine on amazon (here) for much cheaper than what the sell on the sony site. I got mine brand new and fantastic working.

Go Sony Vegas then give the rest to me! 

I'm kidding, but how many other chances will you have a AAF?
I'd get it while you can, you may never have that much money to spend at one time again, you can always buy bricks in small amounts, but you'd have to save up for AAF, so get it while you can afford it all at once. SV can't touch the effects of AAF,

I'm assuming that you have a good camera, so really the only other thing that you'll need is bricks, and that's one thing you can't have too many of. And if you get AAF from here, then you'll still have quite a bit left over for bricks.

You are actually looking at the wrong thing. What you are looking at is upgrading your AAE to the newest version (CS5.5). The Full price is $999.00. Sadly, this software does not come with a student discount, so you can't get 80% off. On amazon, you can get this version for around $600.

While you cannot get after effects with student discount, you can get the Video Production suite. This includes:

• after effects

• premiere

• photoshop

• flash

• illustrator

• and more

This bundle costs $1,699, but with a student discount, only $449.If you've won $500, I say this is a no-brainer. If I had that money, I'd absolutely get this.
If you want something a bit cheaper, there is another suite in sony vegas. This includes the video editing software (HD movie studio platinum 11), but also comes with hitfilm standard, a vfx software. This bundle costs $195, and I haven't been able to find it on amazon anywhere that offers a price lower than what sony offers.

I think the C920 is the best thing you can get without going to a DSLR.
BUT, some have said that it doesn't have manual controls, while others have said that it does, so you'll want to research that. If not, the C910 is the next best webcam on the market.

The C920 is about $80 and the C910 is $73 So the C920 is a much better deal, if it has all the manual stuff.
(The C910 has been around $60, but it's price varies a lot. You'd just have to buy it at the right time.)
I really don't think there's any other webcam that even comes close to these two.

Student discount of Production Premium FTW!

What about manual lighting and white balance?

So I guess what I'm looking at is either buying the Rebel T3 locally for $339 and saving for Sony Vegas, buying Sony Vegas and the C920, or vice versa of the first option. Whats best?

No, that is a pro only feature. If you planned on this feature for actually getting rid of rigs and such, I would such you still do it in a photo editing program, even if you had the option of masking in sony vegas.