You are going to have to grow your own fertility. Investigate which crops grow well in your area - ask local farmers. While you are at it, ask about free biomass - sawdust, old hay, grass clippings, etc.
If you want to start with a series of raised beds, each 4x8 bed will cost about $25 per bed for materials and another $25 for soil. This comes out to around $1.50 a square foot. Here is a list of those crops that generated a value greater than $1.50/sq ft for me last year: Celeriac, Basil, Pole bean towers, Pumpkins, Carnival squash, Salsify, Strawberries, Garlic. Other farmers could likely give you more examples.
You could always do raised beds without the lumber too. Then the crops that pay for themselves the first year increases to over 20. In other words, buying soil is cheap. Right now you can take advantage of cheap gasoline prices for delivery IF you have enough capital upfront. I prefer to make my own soil and amend what I already have, but in your situation, you may just want to bite the bullet for a couple of years.