What is the normal cost to fix a foundation crack?

Could be as cheap as $3.87.

Hairline cracks are common and don't necessarily mean you have a problem. If the french drain was installed correctly you may never have a moisture problem. Water goes thru solid masonry too.

Agreed! However, what I am worried is the crack will be worse with time going by. Also this crack will increase the radon level in my house.

In my experience the best way to fix a crack is from the outside.

This involves typically digging down to the weeping tile, finding the crack, cleaning the surface and then sealing the crack with both sealant and a membrane.

Sealing the inside wall doesn't prevent the water from entering your foundation.

I've done this myself several times simply using a shovel and simple hand tools.

Depending where the crack is you may need to avoid gas lines etc. Reviewing your blueprints and approving the dig generate additional cost.

There are guys who use epoxy to seal cracks. You could also use hydraulic cement. Dam It is one brand I've used. Use the slow setting version. But if you are worried about water pressure on the foundation or radon, fixing the crack will only have a temporary benefit.

I got a crack fixed in a foundation by the "Crack Team" in the St. Louis Area last summer and it cost $250 -- which also included epoxy sealing around a pipe that entered the foundation wall at another location.

It was a crack that extended from the floor to the ceiling -- 6 or 7 feet.

One thing I would mention about sealing around a pipe entering a building is that if your builder is like the moron who built my house, he used a 4 inch corrogated pipe as a sleave for a one inch pipe and then left it in there and just filled it in. I had to rip out his patch and his sleave and patch the hold with hydaulic cement.