Falcon,
DC8-71/73 fully compliant with Europe and noise/RVSM requirements.If you own the airplane and its on something like US register/121 cert it would cost less than a CFM B737F European registered and carry 3 times more ( with the high cost payments on B737-3/4F ) and can tanker fuel to the expensive places in Nth Africa which the little airplanes can't, this is a BIG cost saving.
There are plenty out there I think UPS had 18 with glass cockpit. There are several Sims in United States Pan Am, crews and mechanics are available but all US FAA certified, this may be a problem in Europe and elsewhere as they seem a bit uptight.
The purchase cost is low cost depends on the 4 engines CFM-56-2. Lease would be not much,you would be better to cash buy it. They are a solid "truck" and take 8 ton per overwing position. go 8 hours direct and carry 40-50ton.
4H.