Depending on the temp, you should do fine with regular white sports socks. Wool for sure if oyur in a cold climate.
My personal pref. are the ankle socks, when I gots my boots on, looks like I am not wearing socks, but I get all the protection.
50 socks for 2.99 I would be a bit cautious about though, they might fall apart on ya
I think you can get a back of 10 for about 6 - 9 $ @ Walmart.
And just a tip, try not to go sockless when treking, you run the risk of blister, and the smelly foot thing is not that good in a dorm room
Sandles I guess you would have to bare foot cause ya will look like a senior citizen with socks and sandles