I'm going to echo what a lot of people are saying; fit is a lot more important than the money you're going to spend. What you're going to want to do is find some brands that fit you well, and buy cheap basics from them. Once you figure out what your personal style is go out and buy more expensive statement pieces.
Start with some fitted t-shirts, and none of that graphic tee stuff. Get a wide variety of colors, and some slightly more interesting ones with stripes etc. You can do this for really cheap, check out Gap, H&M and Target. All have decent quality Tees for around $10. Wearing good fitting t-shirts without dumb slogans makes you look 10 times better.
Next, find some good jeans. One of the most important things with jeans is to make sure you find a shape that works for you; jeans come in tons of different styles so spend some time trying on lots of pairs. For example, I've got broad shoulders and decent sized legs, that means skinny jeans just aren't going to work for me. Figure out what you like best, Boot, Skinny, Slim, Tapered, Straight etc. After that find a brand you like and buy 2 pairs. Just starting out, I personally recommend Gap or Levi's. Both are pretty decently priced and often have deals. Each company also has many fits and they'll also last a while.
Shoes: being a college student, you're really not going to have a lot of need for some $500 dress shoes, I recommend not worrying about those for now. Keep your eyes out, and if you see a great deal on sale spring for it. Right now you should focus on buying sneakers. There's a lot of great info about sneakers on these boards. Read about them. Having a nice pair of Pumas or Addidas instead of gym shoes will elevate your look. Since it's fall also look into some boots, I personally recommend the LL Bean Katahdin. Cheap, and classic American.
Since it's fall you should also be thinking about some decent sweaters and coats. Sweaters you can find pretty cheap, any department store should have a decent selection. Get a couple of colors. As for outerwear that's too big a topic for me to discuss here. There's plenty of info here, you can find it. Also, while I don't recommend college students spend a lot of money on dress clothing I do like corduroy blazers. They're arguably the most casual blazer, and they work great with sweaters in the fall. Look through thrift stores, or find one cheap.
While we're talking about corduroys, get some corduroy pants too. They're comfy, warm and look fabulous. Don't worry about the wale size so much, just get a pair you like. These can be bought just about everywhere that has pants, Levis has some, J Crew, BR etc.
Button Ups: get a couple of button up shirts. Not dress shirts, but button ups. Plaid is great in the fall, and you can't do a lot better than J Crew's secret wash shirts. H&M and Gap should also have some decent quality cheaper ones.
Now, don't go out and buy this all at once. Just get the jeans and the t-shirts first. After that start to piece everything together as you come across stuff you like that's at a good price. Check out the WAYWT threads to get ideas.