Best way to prevent weeds in garden without the high expense?

Landscape fabric and mulch will be the best - weeds will always pop up, it is the laws of nature.

If you can't afford landscape fabric and have a supply of newspaper, it works pretty well at keeping down the weeds. It will eventually break down but, a 1/4" of paper will help with week control for several years and still allow water to absorb into the ground. A good layer of mulch, approx 2-3" on top of the papers should provided several years of easy gardening with only a few shallow rooted weeds.

Use newspaper,cardboard,heavy landscape fabric and mulch.

We could not afford mulch. Put down grass clippings and it is working great. Have a 2" layer.

mulch mulch mulch

Layers of newspaper under the mulch. Spray break through weeds with Vinegar and water and some salt mixed in.

Personally, I hate landscape fabric. Eventually it will allow the weeds to pop through and makes them impossible to pull without the fabric tearing up. Removing the fabric has been one of the worst tasks in my 20 years of gardening, never again. I now use cardboard, as another poster suggested. I soak it then add grass clippings (another poster with this fabulous idea) and any weeds I have pulled. Try to get those weeds scalped or pulled before they go to seed and each year you will have less and less to deal with. I scalp a good bit of mine with a coal shovel, easy-peasy. Sharpen the edge with a file occasionally. I have heard that corn gluten will act as a weed suppressant, but since I allow some of my plants to reseed, it would not work for me.

I used Preen in my flower beds and it works great.