Small and medium weapons aren't worth very much, and it's no big deal to pack them in paid storage forever. For example, I have roughly 5000 inventory of random weapons from across the game, and it's only worth ~180k cr. That's 1.8k/month in storage for thousands of small guns. My mountain of medium weapons took up 3400 space and amounted to ~290k cr; 2.9k/month upkeep isn't a game breaker for hundreds of medium weapons. Large weapons have a bit more value, 2400 space worth of big guns was worth ~360k cr. Put all together, we're talking about enough guns to equip all your ships forever, for the total upkeep cost of a few medium ships.
The point I'm trying to get at, is that you can just store all your guns at a planet storehouse. There's no need to rush the colony game or spend millions to fortify your armory world, or to use free storage tricks that don't really make sense. The cost of storage is already low enough that your guns can be cheaply stashed from the very beginning. It's a different story with space ships, as the storage price uses their full market value. It's very possible to build up millions of CR worth of ships by salvaging everything you fly across, and the price of 1 month of storage can easily exceed the sale price of the ships. Ship storage definitely warrants building up your own colonies and defenses for the cost savings.