I'm not sure where you are or what your growing season is, but in many places it's a bit late for starting from seed.

We have free seed banks and exchanges here that are taking orders online and delivering to your car.

You might want to check the farmers markets (still open here) for starts or even the grocery stores! Depending on what you want to grow, you can probably get out the door for $20-40.

Actually, in most of the United States, last frost is after this date. But even retail, seeds are pretty cheap, and what you get is likely to be of high quality. Second-hand seeds are often free, but might be of questionable quality. That being the case, if you have local gardening groups, there may be people who have extra (or slightly old) seeds they don't mind giving away. Be aware that the cost of soil amendments and fertilizer is probably going to be a lot greater than the retail cost of seeds.

Besides very cheap seeds at your local big box stores ($1-$2, lowes/homme depot), you could start quite a few plants by picking seeds right from what you eat (tomatoes, bell peppers for example).

Walmart has avseparate rack of seeds for 25-50 cents! Plant any potatoes that are sprouting.

Thanks everyone

Re picking seeds from what you eat, be careful. What you eat are likely hybrids. So picking seeds from those fruits will get you who-knows-what. Almost certainly not what you ate.