Think about what's in those little jars and that's when you start saving money. You can do this yourself. You already know about introducing your child to new foods slowly, so here's how to make those simple foods that they love. If you just want to give your baby a simple vegetable like carrots, then put carrot pieces with some bottled water into the microwave and cook until they are tender. Then puree the carrots until they are the right consistency for your child.
Bananas are even simpler.
Just mash them and add a little breast milk or formula to desired consistency. As I gradually introduced my children to new foods I finally ended up just taking what we ate and putting it in the blender. They had spaghetti, beef stew, mashed potatoes, simple soups, etc. Once you have made your smoothed out dishes then put them in an ice cube tray and freeze them. You can pop out those little chunks of baby food and put them in a Ziploc bag, label them and put them back in the freezer.