From the FHA handbook (bold added by me):
"The appraiser must indicate the extent of repairs and note this in the appropriate section of the appraisal,or in the “additional comments” section, or in an addendum, under the heading of “Reconciliation –Required Repairs” listing the repairs noted together with an estimated cost to cure."
So, if folks are doing FHA appraisals, and are requiring repairs, and are NOT listing an estimated CTC, you're out of compliance.
To the OP: FHA doesn't require you to 'report' the source of your estimates - only the estimates themselves. Whatever source you use, though, I'd keep a copy in my workfile. So long as you have documentation of where you got the estimates, I really doubt a state board is gonna push to hard about whether those are accurate or not. To J's point, using a range is a bit of a CYA as w