Recently I read an article that gave me a way around the lack of vegetable seedling on the shelf at Bunnings. It was entitled "23 Fruits and Veggies you can Grow from Scraps". This was probably the sort of thing that you could imagine our grandparents doing to propagate veggies for their patch in the old days; and it still works today - and here's proof.
Celery - grown from the leftover base of the celery with a few tiny leaves left intact, watered each day and left inside in direct sunlight. Roots have built up over about 2 weeks and the leaves have multiplied and grown to about 150mm.
Spring onions - the same sort of treatment as the celery, starting with the bit you cut off when using them to cook. Although not as advanced as the celery it shows how you can just do the same thing in the garden, harvest the bit above the root zone and then let it re-shoot into a new plant. You'll never run out of spring onions again just as you're getting started on that stir fry!
Lettuce, cabbage, bok choy, lemongrass, potatoes, fennel, the list goes on - note: peaches, nectarines and plums will take a little longer to harvest.
It may not seem very macho to get interested in veggie growing this way but it's wonderful to see a usable plant evolve from a piece of scrap which might have become compost otherwise. Isn't nature wonderful!