Quite a few Regia Aeronautica kits were limited run only and are therefore rare.
The Alphaflight release schedule of highly detailed 1/48 resin kits was ambitious to say the least and were available only for a short time through Pacific Coast Models.
Classic Airframes RE.2001 kit was the only injection moulded 1/48 model of this aircraft and has been OOP for some time. Classic Airframes S.79 kits are considerably better than the Trumpeter kits, which have shape issues and the Flashback S.79 is the Classic Airframe kit with extra resin and etch parts.
E.P. Originals 1/48 resin kits were short lived but were good quality.
All Italian Classic kits were complex and highly detailed 1/48 resin kits.
NOIX Models are perhaps the best of all, being exquisitely moulded 1/48 resin kits of the entire range of Schneider Trophy aircraft. They have commanded high prices since production stopped.