Mudjacking estimating cost

[Jacques Cyr]

Have a off-market lead for home near Grand Rapids, MI. Sounds like the seller has issues with a breezeway between house and garage. The Slab for the breezeway is in "bad shape"; however, they got a quote for $25,000. I'm trying to get a better understanding of what's involved with the $25K estimate, but that seems "Very high" for a 40 sq ft slab. (Assuming 4' x 10') (Though seller said, "400 Sq ft. Not sure how that can be, having view a general front elevation photo - not specific). 

Thoughts on general budgeting cost for mudjacking? Essentially, I'm trying to get rough estimate if "worth pursuing" as they owe a good amount on current loan, etc... 

Thanks...
Jacques