How many skirts should I plan on having?

I’m heading to college, and the dress code is knee length skirts of dresses. So I’m looking at skirts, and wondering what kind I should get. I tend toward floral prints, but recently I’ve really come to like solids. I’m thinking about getting a 3 pencil skirts, a black, grey, and jean one. Then I’d like to get 3 sorta “twirly” ones for lack of a better word. You know, the ones that are full, and when you twirl, they twirl with you? Yeah, those. Probably 3 of those. Then I’m looking for 2 ankle length skirts, one jean, one kahki, which I have yet to find, any ideas on store to look at? And I’ll probably get more as I have more money, but do you think that’ll be enough to get me started? I’m also trying to find some day dresses, kinda casual, but not like walmart brand casual. Like shirt dresses, and wrap dresses made of cotton. That’s what I’m looking for. So if you have any ideas for me, or good store to look at, nothing crazy expensive, I’m looking in the 10-30 dollar range, cause I’ve only got 500 saved for wardrobe. Thanks guys!