Well actually the price of concrete goes up and up, not up and down.
But seriously, I have a friend who does poured concrete foundations and there are many variables that have to be taken into account.
He has a base price for an 8"X16" footing with an 8" thick 8' tall wall.
Add for 9' wall height
Add for frost footings
Add for 10" thick
Add for 12" thick
Add for brick ledge
Add for door and window openings
Add for garage
Add for slab ledge in garage
Add for porch haunches
Add for pier footings inside basement
Add for pump truck if required
It goes on and on like that, where you are located can make a huge difference in what you will have to pay.
I would talk with someone locally and let them give you a preliminary bid on it. Just bear in mind that pricing in 6 months to a year from know will be higher.