Some ideas, if you choose the "big" garden route you could also do honey bees which would help your garden cause and sale the honey with the veggies.
Asparagus is an easy one, we have 50 plants and have 50 more on the way to plant. Once mature you can cut daily for 6 to 8 weeks. My 50 plants give me a bundle a day, at $4.00 a bundle over 8 weeks that is $224.00 a year. They produce for 15 to 20 years from the original root that was planted. They do not take up much room in my garden, plant 1 foot apart and space rows 2 feet apart. I grow Jersey giants which yield less than the other varieties. Grow them free of chemicals and you may up the price. The $4.00 mentioned above is market price here for non organic.
My daughter is 2 and we have chickens and sale the eggs. The money is hers, she helps every day feed and get up the eggs. I sale them for $5.00 a dozen, not certified organic, but the feed is free of growth hormones and bi products. this is easy money, laying hens require little work.
The chickens mentioned above we started to help teach our young girl responsibility and it works. At 2 and some change she knows every night we have to get up the "babies" eggs and make sure they have feed and water. this has also helped her learn to count, she counts the eggs and the babies each night to make sure none went missing when they are on the roost.
Just some ideas above.
I think the real question is how much do you want to make a year, that will dictate what route you go.
Good luck.
Jay