Some of the ingredients are costly, but when you look at the long-term results, they are an investment in your healthy soil. Rock powders, dry molasses, orange oil for pest control,
beneficial nematodes,
mycorrhizal fungi, dollars spent upfront and then a few things for during the season mean you'll have a healthy crop in your garden. The costs of chemicals aren't just in the dollars spent to kill all bugs or all weeds, but in your health and the health of the soil. I think you'll find that some things don't need to be done every year, or you can stagger it if you need to.
If the budget is tight (been there, done that) then concentrate on creating your own excellent compost, get the lava sand and Texas greensand (both affordable) and in the meantime, find a commercial compost like Black Kow. Mulch in the garden with wood chips from your yard or perhaps picked up locally. The mulch will break down to fertilize the soil and will hold water in in the meantime.
Foliar feeding can be inexpensive - a bottle of (or make your own) Garrett Juice, plus a few liquid ingredients like fish fertilizer, liquid molasses, will keep them healthy. Liquid applications of water with a very dilute mix of soap, orange oil, hydrogen peroxide (not necessarily all at the same time - see the guides) will help keep the pests down if you start to see them.
Your best bet is to be hands on in your garden, learn what the insects are that you're seeing, remove pests by hand when you can, and treat in a way that you don't kill off all of the beneficial insects.