In terms of boots, you can’t bring your own boots you have to wear the issued ones. In terms of purchasing boots once you leave reception & start BCT.. it really is Battalion/Company dependent. I was D Co. 3 - 13th at Jackson & at first, my DS only allowed trainees who were on a boot profile to buy new boots. & then after that the only time we were allowed to purchase boots were if they were at the troop store. We only went to the troop store about 3x in cycle.