[Finalgenesis]

Also consider that while yes lvl 0-2 covers most sites, the "super" sites are mostly sprinkled in lvl 2-3 sites.

A quick look in the DB gives me (roughly, noobie judgment on units):
lvl 2 sites - contain 12+ sites with worthwhile mages/unit for hire, 14 discount sites
lvl 3 sites - contain 7 sites with worthwhile mages/unit for hire, 10 discount sites
lvl 4 sites - contain 1 site with worthwhile mage for hire, 3 discount sites.

It may be very worthwhile to go for lvl 3 search, a discount site or the right worthwhile mage hire can completely change your game. As for lvl 4, I wouldn't bother if you have to spend any tangible effort to get it (eg. taking pretender with 4 pick in a path instead of 3 solely for search when bless is not a consideration).

I didn't bother to look in lvl 1 or lvl 0 sites, I do recall there is a rare sprinkle of lvl 0 site that gives discount, The Oven for construction and the Cedar Pillar I think for example.