Installed by a landscaper:
Pavers $13-25

Natural Stone $18-40, depends on stone

You can, if the thought appeals to you most, sit at your computer for a number of hours searching for designs, and will no doubt find some. But there is a limit to what services your computer will spit out to you, and more specifically a limit to how well a design found on-line will suit your yard or the stone you want.

Or, you can head down to your nearest library, bookstore, used bookstore, or magazine stand, and can acquire in one trip a whole armload of inspiration with which you can design precisely what you need and want - without getting carpal tunnel syndrome or any other computer-related cramps.

While you're out of the house, you could also stop by a local landscape supply yard (ideally not the big box kind), and look at the rocks and concrete blocks and look at the price per square foot that is usually posted for each kind. Add a bit of money for whatever sand and gravel you'll need for a base in your climate, factor in what you need in terms of equipment rental or hired help, and boom, you're ready to go. Canada's a big place, sorry I don't know if my recommendations of good local yards would be a help!

One thing to remember when buying stone, especially flat stone to lay for patio's and such. Know your square footage. The landscape place or the quarry where you get your stone will be more helpful to you if you know how many square feet you want or need. They'll be much quicker helping you find a stone and prices too.

While I'm not in CA, our local stone business has already computed what each ton of stone will cover, i.e., my garden path irregular 3" thick stone, PA Quarry Steppers Fieldstone (flat on both sides) covers approximately 60-70 sq. feet. They have printed sheets of paper with the names of the various stones and prices are per ton. You also have to add in delivery charge. CT Fiedstone Flagstone goes for $283/ton. Also you will be surprised at how heavy each stone can be!!! so where the company is able to deliver the stone makes a difference....some will only leave it in your driveway, others (ground permitting) will deliver it very close to your site.

My Quarry Steppers cost $190 USD/ton, so for your deck you would need about 3-1/2 tons (200 sq. feet) + delivery charge, and the necessary base material, etc.

I have a large wood deck also and someday hope to have it replaced with stone....

Unless you have lots of time, lots of muscle power, and can rent things like a 'tamper' to pound down the base before setting the stone, I would opt to have it professionally installed. You also have to consider how you will remove the dirt and where you will put it as you prepare the base area.

As for the front steps, I would definitely have a stone person do those.....I had to have mine redone last year as the frost heave under the steps kept lifting the columns to the front overhang and pulling it away from the body of the house. It was quite a project to find the source of the water getting under the steps and correct the problem.

Patio installers frequently have brochures with designs using their products. Does Canada require 'Permit' to do this type of construction?...another cost to add in to your budget.