He subsequently hired a contractor, who got the appropriate permit(s), and started work on the house.

In most counties (Not Maricopa though) the lien holder is offered the subsequent taxes first. 

I was hoping to find one that was not sponsored by a commercial enterprise - you know, something completely objective.

I searched the forums and found similar discussions about relocating and subsequently getting bank relationships back up to speed in a new area.

The affidavit of a person knowledgeable of the facts to the effect that notice was given is prima facie evidence of notice in an action involving a subsequent bona fide purchaser for value if the purchaser is not in possession of the real property and if the stated time to avoid the forfeiture has expired.

But now you cannot subsequently use that same person because if you try to use the same mismatch again, the IRS will recognize that and issue a fine to you.It does suck that there are so many contractors out there dodging their taxes that the IRS had to come up with such draconian measures to gain greater compliance.But also, ask yourself this.If your contractor is skirting the tax filing requirements, what other corners are they cutting? 

What criteria to use and subsequent websites to use to narrow the search before reaching out to realtors and property managers for more information within that specific market.  

However, your older certificate already is one year old and you get to hold it without buying any subsequent taxes.

(That was in 2014; the market has continued to increase so each of our subsequent purchases cost increasingly more than the last.)

Depends on your purchase order and subsequent expenses.