Nice thread, just a few things I might consider:
And in the end you probably won't get the site.
That's great if your system includes your pricing influencers in their entirety but for some people there are other things to consider.
1. Are you truly good at SEO or search marketing or even Internet marketing? If so, or if you know of a good company that is affordable to you:
A) I would strongly look at how many popular keywords(targeted) this site ranks fairly high for but not quite top ten and consider the effect on targeted visitors obtaining those top ten positions could produce. (I'm in escrow on a site right now that is very close to some money keywords and with a little help will see huge increases in traffic)
B) I would consider what cross linking (or for the more marketing types, "cross promotional") opportunities exist with other sites in your portfolio. (Site I referenced earlier is also great for adding a few targeted one way links to an existing site of ours)
C) Are there flaws in the existing (assuming they are PPC'ing) PPC advertising efforts? Could more ROI be squeezed out of the existing spend or are they failing to target a goldmine of different key phrase nuggets?
D) Is the site's architecture flawed? For instance, are search engines able to spider and index all the content? If not, can you feasibly make that content spiderable/indexable and increase traffic (by a little, or even a lot)?
F) You have to consider what improvements you could make to the site: Can the site's sales channels be improved, can conversion rates be improved, is it properly offering its entire demographic products or services that they would find useful while maintaining customer satisfaction to a high degree?
2. Are they your sole or one of your few competitors? Getting rid of the competition can do wonders for your business (gee, no kidding?)! Narrowing it down or becoming the big kid on the block can also help greatly too.
3. Are there any sombrero negro issues that might lead to search engine banishment or penalization in the future? Link schemes, cloaking, doorway pages, PFPR (pay for PR), duplicate content, etc.
Gotta run, hope that helps add some extra considerations into the mix.