Why did this turn into a discussion about cars? lol
lmao
For the partyhat and specs you could make it so that you exchange 1 blue partyhat and a certain amount of cash for it. (e.g. 5b cash + blue phat = partyhat and specs).
For the wise old man hat you could make it so that you exchange 1 blue partyhat, 1 santa hat and a certain amount of cash for it. (e.g. blue phat + santa hat + 5b cash = wise old mans hat).