Even later on (meaning around level eleven or so), you will be able to buy the gun from Mike the Plumber. This will negate the need to ever hide anything in your safe again. When Jesus and Jhamal come up to the door, you’ll have the option to shoot them. Now, when you choose the option, not only will they NOT get anything, but you’ll get some extra cash for blowing them away.
But back to the store, though. You can buy up to 12 pots at a time, and you should try to maximize the number of pots as quickly as possible, so that you can maximize your weed output. You’ll unlock the metal pot at level 5, which lets your plants use only half the water to grow, and the alien pot at level 11, which allows your plants to grow with no water whatsoever.
Whenever you want to replace your old pots with new pots, you can tap the stool that a pot is sitting on, and the option will be given to remove that pot. Then you can replace it with a new pot. Or later on, when the cop, Mr. Malone, shows up, he can take your pots for you.
Mr. Malone will need a bribe to go away, to the tune of 500 cash per experience level that you have. If you don’t get rid of him, he’ll steal any pot that has a seed and/or plant in it. That makes him that much easier to get rid of without a bribe, though; just harvest all of your plants and then tell him to piss off, and he’ll go away.
See the panties option that Nancy has, that unlocks at level 14? That will get rid of the cop as well. When you buy the panties from Nancy, they will automatically get hung on your wall. Then when the cop comes, get rid of him by telling him to piss off, and he’ll go away regardless of whether or not you have any plants sitting in the pots. He’ll take the panties with him instead.
Other unlocks in the store are fairly straightforward. The different strains of weed are simple enough. Bush weed, the original, yields 10 per plant. Northern lights yields 15 per plant. White Widow yields 30 per harvest. Purple Haze yields 25 per plant while the top strain. Alien Crossbreed, yields 30 per plant. All of them yield the same experience points per harvest, a total of 3 experience each.