Gardening question... need cheap dirt!

I am getting ready to plant my balcony vegetable garden this weekend and I need some advice about soil.

Last year, I just bought cheap organic top soil I didn't have much luck with my garden, but I think that was mostly due to the containers being too small for the plants.

I did more research about soil and I'm told all over the place that what I need is potting soil. Unfortunately, that's more expensive than top soil and black earth (which is always on sale at this time of year). From what I understand, the problem with normal gardening soil (I'm assuming that's what black earth is) is that it's not porous enough and turns into hard clumps when wet. So what if I bought the cheap black earth, combined it with my leftover dirt from last year, something to make it porous and some plant food and/or manure and/or compost... would that do?

I know that the ideal would be to buy all potting soil, but I would be looking at a good $50-60 worth of dirt if I did that.

Well if you are planting in containers -"container potting soil" technically is the best but it does dry out pretty fast. Do you know if there are any yard waste sites nearby-the compost they have is free!!. You could get some topsoil, add compost and perlite (or is it vermiculite?) mix all together. That should work. Osmocote is a long actiing fertilizer that would be probably the best. Or post a wanted add on craigslist/freecycle for this.

You might also be better calling around for topsoil as the place I get mine is a "potting soil mix (I use in place of plain topsoil) and it has topsoil/compost and aged/composted manure. That stuff is great and many places might have something similar.