In that case, reselling physical goods manufactured by others is the simplest thing that might work.

For example, stand on a bustling corner with your hotdog cart (around lunch time of course). More people eat hotdogs than buy JavaScript frameworks and more people will gladly pay three bucks for a hotdog and a Mountain Dew than for a bookmark manager.

a very limited budget

If you are undercapitalized for your business idea, start a business where you are not. Running out of money is how businesses fail.

a waste of time.

Having ideas is almost always a waste of time. Ideas where the first step is spending money are usually a waste of money as well. Having ideas is easier than doing something and spending money is the easiest thing to do because shopping avoids rejection and it’s nearly impossible to fail at shopping.

Good luck.