You can go for this as you play by buying supplies from Tweeks coffee shop, Jimbos gun shop, the hobo at U-Store, Mr. Makies PTA table, City Wok and Toms Rhinoplasty shop. you should be able to unlock this without much difficulty unless your going for the junk hoarder achievement then you will have to sell your junk for the money to spend after the last boss fight at the end of day three.