Poor man's potting soil: When you really don't have the money to spend on soil, overturn your pots from last year, break up the soil with your new hori hori and return it to the pot. Add a little new soil if you have any and you're ready to plant. Yes, you will have to fertilize more but a little bit of fertilizer can go a long way.
Make your own: Go to any bulk gardening supply store (if you live in Portland, Concentrates Inc is a good place to purchase soil amendments) and buy several large bags of peat moss and perlite. These are the basic components to any store bought potting soil. In a large (clean) garbage can mix the two together-one part peat to 1/2 or more perlite depending on your needs. Use a shovel and mix until it looks evenly blended. Add bark mulch, your own compost, fertilizer, mycorrhizae or moisture absorbing polymers if you're so inclined. Make your own soil mix instead of using peat if you stay up at night worrying about exhausting peat bogs. Just make sure you use sand, perlite or some other ingredient that works to prevent compaction.
Pots, of course, dry out more quickly-You will need to water every day and fertilize regularly depending on what you've got going. Make your watering a habit-do it at the same time every day while you'll sipping your coffee and dreading going to work. Make watering easy and fun-and for goodness sakes, get a good watering can and buy a new hose. There's nothing worse than those old crusty hoses that curl up and kink every time you sneeze. It's the simple things that make daily life good.