Also the cost of your time. People always forget labour costs.

Also, tomatoes require pretty much the same Ph, moisture, and light levels that Marijuana does. Once you're good at growing tomatoes, you can switch to a more profitable crop

My MO is much cheaper. I just throw produce waste into a corner of my back yard and see what starts growing. Right now I've got about 10 pumpkin plants taking off like crazy. A jalapeño plant too!

I do think that numbers here are much more complex than people give them credit for, firstly no gardener I know only grows six tomatoes and secondly there are added benefits which come from it being an active hobby plus various health benefits.

I think there are bonuses that are very hard to get elsewhere, making friends by sharing excess harvest for example - if you brought tomatoes and give a bag full to someone you barely know they'll think you're odd but give them a bag of ones you've grown and next time you see them they'll tell you how nice whatever they cooked with it was and at some point they'll probably give you a couple of courgettes or invite you to pick from their strawberies while they're away.

It gives a real connection to reality and passing time too, watching your plants struggle from the soil, potting them up and helping them through the various stages of life until they're fruiting and ready for harvest. Watching the weather, keeping track of how much it's rained and when to plant different things or what to water and feed - it's very grounding, especially learning to accept whatever comes because you can only do so much and the rest is out of your control.

I could go on but just one more thing, having excess fruit opens up so many possibilities that you'd never bother with otherwise, making pies and jams just to make use of them feels so good and it's such a great way to discover new things - my dad made a recipe he found for courgette cake partly as a joke in a year they had a bumper harvest and now it's everyone's favourite cake.

Actually one more thing, I was away from home recently and had to buy things I'm used to picking, herbs are insane prices! And awfull quality. A widow box full of herbs saves about twenty dollars a month and that's without even taking into account having a tub of coriander (cilantro) for mojitos.