Peanutter, TBH, all chooks need is a covered place to roost, where they cant be attacked by other critters.
You could lock them in your garden shed at night if you wanted too, if you could teach them where roost, then you could just put straw or woodshavings undertheir perch which you would clean out once a week. Bales of both are about $10 ea.
A bag of good quality food will set you back about $20 and last you 2-3 months for 3 chooks.
Chooks, you can buy from most produce stores for under $20 each or go direct to a breeder and buy a heritage breed that looks prettier and lays for longer (but prolly wont give you an egg a day- maybe 4-5 per week, but times 3 chooks is still over 1 doz per week) for $30-$50 per bird
If your yard is secure and you can fence off the vege patch and anything else you hold sacred/or is a bit fragile, then they can just freerange all day.
If you need to buy a pen/chicken tractor, expect to pay a minimum of $200 and a good one for $5-600. if you have a handy hubby, I can direct you to a great site.
Chooks are pretty easy...