So here is my quick analysis of the coverage rate for Nearmap -...

So here is my quick analysis of the coverage rate for Nearmap - ie how much area can be covered per day.
It is based on today's (20 Feb 2019) Handel Aviation flight of VH-ZID (from Hervey Bay to Cooloongatta covering Hervey Bay (in part- part was done yesterday) and Maryborough.
FlightAware Link: https://flightaware.com/live/flight/VHZID
Aircraft: Cessna Centurion Piston-single) C210
Total Flight Time: 3:06 (ie 3 hours  6minutes)
Flight Speed: about 280km/hr (plus or minus up to ~10%)
Flying Altitude: 2300m (fairly steady)
Flight Pattern: Parallel tracks (flown in alternate directions) with spacing approx 1.7km
So, Notional Coverage Rate: 476 square km per hour (ie 280km/hr x track spacing)
Maryborough covered by 4 tracks of 20km ie 80linear km (136 square km)
Hervey Bay (part) covered by 180 linear km (306 square km)
The previous day's flying was more productive (start and finish at Hervey Bay) with seemingly about 3 productive flying hours covering over 850 linear km about 1450 square km.

Now somewhere between 400 and 500 square km per productive hour (and maybe 3+ productive hours on some days) seems pretty good, and pretty cheap!!