Agree with TJ Maxx - if you’re willing to put in the effort to browse through the racks (and the possibility that you won’t always find what you’re looking for in one trip), there are some great designer finds for way less than retail price. Also browse through department stores like JC Penney, or go to outlet stores when there’s a big sale.
But at the same time, people care way less about what clothes you wear in college - there won’t be some prep squad/clique judging the quality of your preppiness. No one will care if you’re getting off brand stuff. Also, you could start off with clothes that are necessary on an everyday basis, eg. a North Face fleece jacket for fall.
Judging by your username, you’re going to be in Boston? If you don’t own a winter coat already, do NOT buy a Canada Goose winter coat. They are ridiculously overpriced and you will find much cuter and equally functional winter coats at department stores for way cheaper.