At over $2 million each, I hardly consider them disposable
but perhaps they do need to operate at higher altitudes to stay out of range from small arms fire. The plane itself isn't much more complicated or expensive than your average homebuilt and uses the same Rotax engine as many homebuilts. The expensive part is the mission electronics. There are some very capable systems on those little planes.
http://www2.acc.af.mil/library/factsheets/predator.html