Before you buy plants, look closely at how many plants there are in the pot. Sometimes you can find up to four or five plants in a single pot, for the same price as a pot that has only one plant. Use a sharp knife to cut the roots, rather than tearing them apart.
A piece of card board will kill grass and weeds better than a roll of the black plastic stuff sold for the purpose. Save flattened cardboard boxes year round and you will never have to buy anything to kill grass and weeds, and the cardboard will compost. Try to use cardboard with only minimal amounts of inks and dyes.
You don’t have to buy pots for plants. Almost anything can be used to grow something in. Buckets, trash cans, plastic food containers, baskets lined with plastic – anything that can be cut or drilled to allow water to drain. Save the flimsy temporary pots that your plants come in – they work just fine.