A garden will cost more time and money than grocery store produce, but
only for the first couple years when you have to buy seeds and
hardware. After that, it's time, water, and time. If you have those in
your bank to spare (especially the time) you'll find home grown produce
well worth the investment. Buying my tomato plants was about 19$, but
I've been eating cherry tomatoes - at about 4$ for a box in my local
store - by the handful every day, with plenty to give to family and
friends.

The biggest way to save gardening cash is to McGuyver your own shades,
trellises, seedling cups, etc, instead of buying trellised and such
from a store. One tomato trellis might cost 5$, but a huge roll of
sisal twine will cost about 3$, which if used creatively can tie up not
only your tomatoes, but your gourds and dog too, with plenty to spare.
Things like that trim a LOT off the cost.

Of course, if your husband is anything like mine, you'll have to get
out there and prove it. Our tradition is to bet a box of doughnuts on
things like this. I've eaten doughnuts from every pastry store in the
city.