How likely is one to recover data off a bad CD or USB thumb drive?
And how much does data recovery cost? (Ballpark figure.)
Bad CD as in scratched? If yes, how bad are the scratches?
If the scratches are not too bad you can try fixing it by applying a tiny amount of toothpaste to the scratch and rubbing in with a dry lint free cloth. Then try putting it in to several drives/players, some are more precise than others.
If this fails you can use some software tools to try to retrieve/copy the data.
Re the USB flash drive, please describe how the files got deleted, plain delete, format, physical damage, or can't find partition. Based on that I can try to help you recover the files. One thing is sure, don't use the flash drive at all until you're ready to recover the data.