If this was a deal in my hometown where I knew the local market inside and out.... I'd pass (EDIT: on the appraisal, not the deal). But AR makes very good points.
Appraisals, even when done by a professional don't mean much to me. As a RE investor, every time I have to pay for one where a lender is involved, I roll my eyes because (even after the correction resulting from the negligence during the housing bubble creation), the appraisal comes in just a hair above the contract price. I always ask my loan officer.... what good is the appraisal that you demand to cover your risk (and make me pay for) when you disclose the contract price to the appraiser!?!? I always offer: "Since I'm paying for this, why don't we order the appraisal from your preferred company, but not tell them the contract price.... to see how good they are at their job. And get each of us a meaningful number." They never have a good answer.... but the obvious answer is: without knowing the contract amount, appraisals would be all over the map, and unless appraisers wanted to purposely err on the side of over-valuing (which wouldn't be in the interest of the lender) ... the result would be an increasing number of cancelled loans and contracts because the appraisal value was lower than the contract amount!!
If you do get an appraisal, please don't disclose the contract amount!!
I've also (nearly) been burned as a seller. I bought a starter house in a solid blue-collar hood for $56K. Lots of elbow grease, rehab, DIY improvements, and 6 years later I listed it FSBO for $72K. Got an offer and a contract for $72K. Appraisal came in at $63K. I spent the time to provide my own comps, wrote a letter to the appraiser and the lender of the potential buyer, listing the comps and asking for a re-appraisal/adjustment and got them to adjust their appraisal to $72K. By that time, the first time potential buyers walked.... definitely scared off by the low appraisal price. They probably thought I was trying to gouge them and may have been relieved that the appraisal saved them from overpaying by $9K. At the time I was so furious with the appraiser that I could not see straight!! I was told by the lender to the potential buyer (before the re-appraisal) that since this appraisal was done as part of an FHA loan, it would stand for 6 months for anything involving FHA or VA. Even if another buyer (in the FHA or VA program) came along, the lender could not choose another appraiser or get another appraisal until that one expired in 6 months. So if the adjustment hadn't been issued, I would have really been screwed.
I wound up selling about 1.5 months later for $71K. The appraisal came in at $73K.... surprise surprise. The original appraisal of $63K was of course very professional, had comps that averaged out to $63K. But in a 1.5 month period I had two buyers willing to offer $71K.
I'm not saying that appraisers are inept or corrupt or that a single appraisal is completely worthless. I think the value in a single appraisal comes from the details of the comps, not the "final number" given by the appraiser. But that requires you to "dig into" the comps and see how they stack up against the property in question. But in my opinion the only way to get a reliable estimate is to take the average of at least 5 appraisals done by appraisers who don't know the contract price!! Since that's obviously not cost effective, I'd look for some other way to be confident the place is worth what you are paying.