As others have stated the Guild Market changes . The higher level resources are tradeable in any event so available for all levels . It is not unusual for guilds to give their lower level members high resources like cannons to trade with. Trade is and should be a huge part of the game. Its up to the individual if they save it or trade it, let them decide what is and what is not a better offer. I agree they may not want to buy them with guild coins when they reach the level currently required so that is even more an argument for them buying when they feel the time is right.