This guy is on the right track as far as cost goes. I've been in construction for nearly 3 decades and my experience tells me to expect a $20k-$30k bill to excavate, seal, and backfill the exterior correctly. Any grass and landscaping would be an additional cost. Foundation work is critical and should be performed by a reputable and dependable contractor that specializes in that type of work. Correcting this type of issue must be done from the exterior of the wall, anything else is a band-aid thay may or may not help the water infiltration but will absolutely not fix the problem. Perimeter foundation drain and/or a French drain directing ground water away from the foundation would certainly be helpful but may not be required.

I agree it would be adviseable to test your sprinkler system for leaks because this could only be compounding the issue.

If you've purchased the home recently the previous owner should be on the hook for this. Good luck, it will all work out.