NADA guide says 6,650 for
Low Retail Value
This vehicle would be in mechanically functional condition, needing only minor reconditioning. The exterior paint, trim, and interior would show normal wear, needing only minor reconditioning. May also be a deteriorated restoration or a very poor amateur restoration. Most usable "as-is".
Some of the vehicles in this publication could be considered "Daily Drivers" and are not valued as a classic vehicle. When determining a value for a daily driver, it is recommended that the subscriber use the low retail value.
The car in the ad is much worse off than that. It is more in the "parts car" or "project car" category. Four doors typically have very low values. You don't seem many people restoring them (I am an odd exception with my 64 four door). If you plan on restoring and selling it some day, you will loose your shirt, pants and undergarments. I dumped something north of 40K into my four door 64 Impala, but 'book' value is only $17k. If it was a 2 door SS, I would be close to breaking even. But I never plan on selling. But that gives you an idea of how the values run between 2 and 4 doors.
If the owner maintained that 62 with the same skill as he writes ad copy, I would stay away

You would want to look it over pretty carefully. "Bad fuel" pump may be an excuse to not run the engine because it has other (expensive) problems. And that "surface rust" looks like a lot more than that. Still reasonable condition to restore, but the seller is underestimating the extent of the rust repairs needed.
Looking at recent sales on ebay,
This 2 door sold for $1500, body about the same but with the engine torn apart.
http://cgi.ebay.com/ebaymotors/1962-Chev...=item415e84f537This two door, the seller thought it was worth 3,000, top bid was $2,800
http://cgi.ebay.com/ebaymotors/1962-CHEV...=item35b61879c7