Fliginger's in Morton probably keeps them in stock.
I've picked up blades there. I beat up the blades pretty good in my yard - I've got lots of acorns, hickory nuts, and little sticks that are hard on mower blades. I usually have the blade set very high, which avoids most conflicts, but picking up a nut is inevitable eventually. And I've got the chute closed for mulching, so when a nut gets picked up in bangs around inside the mower before it drops.