How many and what color panties for 15 y/o girl?

I am turning 15 in September. I have a summer job and am getting my first paycheck in 2 weeks. I need to buy more bras and panties, Now, because my dog chewed holes in most of them, I have 1 bra and 3 pairs of panties. My mom knows I need more so she said I had to buy my own. I am going to buy I think 3 or 4 more bras and then I am not sure for how many panties I need. I am going to throw out the ones that I have, and buy more, the problem is, is that white panties come in more, like 6 or something like that, for the same amount you could get 3 colored panties, which is like 8-9 dollars per pack, What colored panties, and how many should I have?