Help I Need Some Kinda BOX?

Okai today i brought my bf his valentines day present and because we wont be seeing each other weve decided to send them in the post THING IS .... i have brought him clothes and dvd ive wrapped them in wrapping paper but i now need a box to send them in i saw them in my local ARGOS but you cant just buy on on it own any obdy help pleaseeeeeeeeeeee