Mold is a 4 letter word for a reason, and buyers hate mold. If you're looking to remediate the existing mold it will cost substantially less than $10,000. However, if you're looking to curtail the existing cause of the mold it could very well indeed be costly. Most buyers don't want to inherit what they perceive to be an existing problem, but if you don't have the funds to have the work done prior to closing, or just don't care to do it, you could always share the quotes with potential buyers. At least that way you'll be deemed honest, upfront, and they'll be thankful you were so helpful.
Keep in mind, this advice is coming not having seen the extent of the problem. Hope this helps. Feel free to reach out to me
Some properties will have a preinspection available to potential buyers. Very untypical on a foreclosure, however. You can always have an inspection done prior to having a contract but you maybe spending money on an inspection for a house that could go under contract with someone else. And since you're talking about foreclosure properties, a lot of times the utilities won't be on until after there's a ratified contract.
Secure the home first, then perform your own, independent inspection.