JimBob,
Forewarned is forearmed. You know ahead of time that the subject's property sales history is going to be an issue and that it should be one of the major themes in any appraisal report. You'll actually be doing everyone a favor if you run down each transaction and listing, talk to both sides of each transaction and find out what did and didn't happen to result in these increases. Disclose this information in your report and include lots of detail about the subject property, verify your comparable data, make realistic adjustments and let the chips fall where they may. Make sure you include lots of photos to back up your quality and condition ratings. In other words, just do what you would normally do for any appraisal assignment.
Observe and report. The more that you disclose, the less wiggle room you leave for them to lay it all on you. Once the lender has the information they can make an informed decision. They can't say they don't know unless your report is insufficient. Really, your appraised value isn't the big issue here; it's whether you disclose enough of the information they need about the subject proeprty to intellgently underwrite their loan. I don't know, but I'd bet that once you run down and disclose all this information, the facts will kill the deal; value opinion notwithstanding.
Don't back away from this just because it's a high(er) risk assignment. This is exactly the kind of assignment that an AVM or 'desktop' appraisal would screw up, and is exactly the kind of assignment that calls for a professional appraiser (you) to do a professional appraisal.
George Hatch