Affordable.... Not likely for everyday farmers. For things like government agricultural departments, working with remote sensing peoples (people like surveying departments or should that be geomatic?), yes, it is affordable, but for a $1000+ an image, with the photo being a couple of days out of date, this becomes somewhat out of touch for most farmers. Normal fixed wing planes also cost too much for everyday use, unless of course you base the government department in a town that is very marginal, and since most of the town relies on the department staying alive, which leads to both political parties spending up big time, then this isn't viable either. Of course, the images produce by these planes are a heck of a lot better quality, remember, only a couple of years ago did we get
Things like the Adelaide University (Australia) project involving photos taken by remote controlled plane with cameras attached, make alot more sense.
Of course, another reason for the delay is because of the military checking of the photos to make sure they aren't of politically sensitive areas :P