In my limited experience of around 75k pieces, I haven't seen a 2x+ ROI on traditional stamps vs. a permit imprint.

One, I want everyone to know the maximum amount that I will bid so I don't lose a potential buyer at the very end over a small amount of money, and the second I want people to know my max bid so if its way high they won't touch it and I don't end up paying doc stamps unnecessarily.

Alphalt drive way vs. pavers vs. stamped concrete.Central vac?

I sent a certified letter with the papers for them to sign, along with a self addressed stamped envelope to the individual who paid the $2,500.

Remember that hand-written mail with a first-class stamp has a better chance of being opened (51% better, I've read).I know of at least one service which has a factory full of robots "hand writing" letters and envelopes with "Bic" pens.

Not sure what municipality you are in, but many towns, especially those where transfer stamps are required to sell, will look at the listing to see if recent work was done.  

Couldn't get transfer stamps because there is only one water line but 2 meters.

Where I am, buildings department has a file for each property complete with architectural drawings, permits, and I believe the drawings are stamped when they were approved.

If you look at the stamp on the top of all the titles and deeds in your county you'll probably see that it says corelogic as a stamp on top.  

Bulk rate vs. stamp?