The Aero-Pac Combi-Tow costs € 1050 + € 120 for wide tires and + € 240 for 95 amps battery instead of the standard 45 amps. The airplane adapter is another € 150. All prices excluding VAT and S&H (quoted € 90 from Belgium to Germany). With all options and VAT, that means almost € 2000.
A neat feature is that you can use it as a starter pack. It's got a dry lead battery (Hawker) and an electronically controlled charger that you can leave connected all the time. Warranty is 12 months.
Aero-Pac will be at the AERO show in Friedrichshafen as well as Schleppmaxxe.