Concrete driveway, should be a minimum of 6 inches.
Buy your lumber in lengths that best suits your concrete driveway project with minimal waste.
Set your string lines and secure the 2x6 form using 2x12 stake's spaced 4 feet apart.
Reinforce the form by placing stake's, at an angle, next to your vertical stake's.

Maintain a 6 inch dirt grade throughout the concrete driveway, if not, dig out high areas and fill where needed with dirt, sand or gravel, then compact the grade.

Install expansion against the garage floor or foundation and city walk. This will allow your
concrete driveway to expand, do to high temperature in the summer months.

Sense concrete is ordered by the yard, you need to transfer square feet into yards.
One yard of concrete will cover 54 square feet at a 6 inch depth.
One yard of concrete will cover 40 square feet at a 8 inch depth.
Example; 16 x 22 driveway equals 352 square feet.
352 divided by 54 equals 6.52 yards, needed for the driveway, at a 6 inch depth.
Always order more concrete than what you need, you don't want to run short.
Order in ½ yard increments.
In this example order 7 yards of concrete.

A minimum 3000 lb concrete mix or greater is recommended for concrete driveways.
Call the Ready-mix plant and order for early morning delivery, with a 6 inch slump maximum.

I just called Folsom Ready Mix (916) 851-8300 and they said that for a 6 sack mix with pea gravel it would cost $120 per yard and that 9 yards would fit on a truck.

There are probably other costs involved but that's the main one.

I would also need to pump the concrete to where I needed it, I think that costs around $1500 or something like that to get someone to pump it for a few hours.

 My driveway is about 25 feet by 45 feet which is a total of 1125 square feet, so I would need 20 yards of concrete which would be 2 trucks and 2 yards. and 21 yards would cost $2520 for the concrete.

I am going to go to Home Depot and price pavers and see what they would cost.