No clothes I own would be worth more than $30, so I'll skip over the fashion debate, but just re: social anxiety at uni, it's worth asking yourself what you're looking for in friends or acquaintances. I've met quite a few people who just needed someone to talk to so that they weren't alone, and they weren't particularly fussed by reliability or catching up outside of uni (which is fine, obviously.) Meanwhile there are others who genuinely want to forge friendships and connections, especially if they don't know (or want to know) anyone from high school in their course.
Basically try and pinpoint whether the loneliness or nerves are stemming from the fact that you're not with anyone, or that you're not with the 'right' people.
There was a great autobiography that came out a few years ago, and I can't remember who wrote it, but there was a chapter to the tune of 'learn how to be alone, cause it's gonna happen quite often.' You don't have to accept it in a really bitter way, but out of all the days and all the breaks you'll have, chances are there'll be instances where you don't have people to hang out with.
Because uni is so
soooo much bigger than high school, it can be a strange transition socially, since you're usually going from a place where everyone knows you by sight, if not name, to a place where 10,000 people pass through daily.
One time, I saw a kid with dreadlocks sitting in a tree on South Lawn eating a sandwich and listening to Taylor Swift. If you did that at high school you'd no doubt get branded Swifty Mc Tree Climber for the duration of your time there, but at uni, no one bats an eyelid
But back to the whole 'being alone' thing, i'd actually say it's more common to see people sitting on their own than in groups. Not only is it nowhere near as stigmatised as in high school, but people will rarely even notice. If you really want to be alone, having a book or some notes open works as a nice 'I'm alone, but it's cause I'm busy and committed, you guys' statement. But if you would prefer to have company, then any of the advice above (talking to people in tutes, joining clubs etc.) works too. I'm sure there'd be no shortage of nice ANers who'd gladly swing by for a chat as well.
Don't eat in the toilets bro, you'll get all sorts of gastro
tl;dr: anyone who judges your fashion sense is a vacuous moron, and being alone doesn't have to be shameful or embarrassing