Gawd you **** me off sometimes. I was offered one of these last year sometime and they wanted to pay $40. I do THOROUGHLY understand Standard 3 and I do THOROUGHLY understand SR-1 and SR-2. They sell it on 30 minutes of work which we all know is BS.
First of all you have to set up a file, read the report and take notes. That at a MINIMUM is 30 minutes. You then have to do MLS search and decide if the comps are good and what other comps may have been competitive and then make a decision as to whether the comps used are he BEST.
In order to do this you have to VERIFY per SR 1-4. That means pulling the assessor data which in my area is $2/each and then IMHO you try to call Realtors involved in the sales for verification.
One has to remember that they are ordering these products because most likely they MIGHT have an issue with the original report which means that the comps used MIGHT have been cherry-picked.
In another post you state Scope of Work. Well, you can't say you don't have to VERIFY (Please see SR 1-4 again) as it is a USPAP REQUIREMENT, so you can't SOW away that.
Any person who thinks you can do this in 30 minutes is an idiot. Let us say it takes an hour; I don't work for $40 an hour, but it won't, if you do it right and abide by USPAP.
And then there are the phone calls or e-mails to respond to and the "corrections to the report" that have to be made that are inevitable. Who in their right mind would put their signature on something for $40? I charge $125 to take photos and write a three page draw inspection with no opinion value.