it's usually better to use methods besides money as a way of letting the players know they can do such things. For example they might take OVER an old stronghold, or build up a group of loyal followers willing to work for them to build one, rather than having the money to purchase it. Often times, if you can seamlessly pepper in these kind of rewards, you'll find some of your players do actually want to buy things related to non-magic items, in which case you should let them do so now, and make the next batches of treasure MUCH bigger.
Also, depending on how stringently you pursue it, 4e has a built in control on magic item production. Technically, players will find gold but need residuum to craft magic items themselves. If residuum becomes difficult to buy in large enough quantities, the PCs may find themselves with a large amount of gold they can't spend on magic items right that moment and thus start thinking of other ways to spend their gold.