Mold is not an easy fix, and you have to be willing to gut the structure (partially or completely) for complete remediation of the mold problem.
Since this “Cheap” house is an investment, be prepared to carry the house for 3–6 months for the mold remediation, sheet-rocking, painting, and more (duct cleaning, additional venting, replacing paneling/cabinets/doors to eliminate mold, etc. Look hard at the numbers, get estimates before jumping in, and be prepared to accommodate the “worst-case scenario”, if the mold is more extensive and takes more time and money to remedy.
Is It Okay to Buy a House with Mold in It? – Homeguides
Can a Home That Has Mold Be Repaired Enough to Consider Buying It? – budgeting the nest
Black Mold Removal Cost: Should I Buy a House with Mold? – Advanta clean
Have a certified mold inspector check the health of the house after repairs, and carry insurance for any liability – mold makes people sick; you don’t want to be sued over it if you did a quick or sloppy job clearing it up.
Best of luck!