Places to buy acrylic nails or idk what's it called help please :D?

OK so I want my nails done for school and change my nails like every wk or two , but I want like certain designs like Hello Kitty and designs like that I most definatly don't wanna go to a nail salon....or make someone do my nails is there a place where I can buy fake nails with Hello Kity on it :) oo and mitch match nail designs :D ? thanksss