I have a fairly large garden and I grew quite a few tomatoes. I started these from seed inside my house in a little greenhouse I have. (It is about 3x4 feet and tall with a number of shelves.) I usually buy seeds on clearance for .10 a packet and freeze them until the next year, so my starts cost me next to nothing. I did buy some special greenhouse starter soil this year for starting some other vegetables with no luck. Putting seeds right in the ground, except for tomatoes I have found usually works best.
Here is my makeshift summer kitchen. I can cook the tomatoes or whatever else I have down without heating up the kitchen. This small cooker cost about $40.00 and my husband bought the propane tank on Craigslist used but I am not sure what he paid for it. It cost me $17.00 to fill it up with propane.
Growing your own doesn't always save much money, but the quality and taste is very good and it is a very satisfying process if you like this as a hobby.