If your pops are buysing state bonds then they have bought all the goods they can of the WM and have a cash surplus. Only the riches pops can affoard to do that. If your Pops are not buying a need (i.e. it's red) and they have a cash reserves then it means that the item is not available to buy of the WM. POPs will only buy luxuary goods if they £100 in the bank. If they have no cash surplus then it could be that the item is available but they cannot affoard it.