Welcome to the forum! Glad you found us!
What are your goals? Why do you want chickens: eggs, meat, bug patrol, eye candy, pets, to show, some combination of these or something else? What kind of location do you have, not just climate but a small urban back yard or a rural area with lots of room? Do you have any existing buildings you can use or are you starting from scratch?
If you are in the States probably the most cost-effective way to acquire chickens is Craigslist, if you can find what you want. The more restrictive your requirements the harder that is. You can also find your state or country thread in the “Where am I? Where are you!” section of this forum and chat with your neighbors. There may be some chicken swaps around they know about or they may have something for you.
But getting the chickens is probably not going to be your biggest expense. The facilities to house them are often a nice chunk of money. If you have an existing building you can use, well that can be a good thing. You might be able to find something on Craigslist pretty inexpensively but you will have to haul it and possibly dismantle it and rebuild it. Usually building something from scratch is cheaper than buying something new like a building from Lowe’s or Home Depot but you have to build it.
If you are buying all they eat your feed bill can get pretty bad. If you grow your own or they can forage for a lot of what they eat the costs can come down.
If you get baby chicks you’ll need a brooder to raise them and a heat source. Some people spend a lot of money on this. Some people get a free cardboard box, say a freezer box from an appliance store, and set that up in a garage or something like that.
Some people buy feeders, waterers, or nests. Some of us either build these ourselves or use something we already have. You can often get free plastic buckets at a deli or bakery, good for feeders, waterers, or even nests. There are just all kinds of other things we use. Some of that depends on what you already have or can get. It helps to have a good imagination.
Some people buy bedding material for the nests and coops, some use what they have. Dried leaves or grass clippings can work as well as wood shavings, hay, or straw. Or cut tall grass if you have it, dry it, and make your own hay. One lady on the US Gulf Coast used Spanish moss in her nests.
There are a lot of things you can do to reduce costs, but a lot of that depends on where you are, what you have, and what your goals are.