By no means a complete listing, here is an overview of Regia Aeronautica aircraft known to have appeared in kit form.  For a more detailed search try this very useful datafile which is found on the Italiankits website. 

Kits by the following can be safely recommended:
Choroszy Modelbud, Flying Machines, MPM (inc. Azur & Special Hobby), Pacific Coast Models & Silver Wings. Also worthy are the Italeri kits (apart from any of the Reggianes).
Broplan, ItalianKits, LF Models & Omega Models have interesting Regia Aeronautica aircraft in their range, but are better suited to the more experienced modeller with good references to hand. You can buy direct from companies such as Airmodel, Choroszy Modelbud, Omega Models & LF Models.

Underscored aircraft in the lists below are linked to a page showing a built example with brief notes.

INJECTION MOULDED


Airfix

FIAT G.50

Savoia Marchetti S.79


Airmodel (vac form)

FIAT Cr.25
IMAM Ro.37

IMAM Ro.43

IMAM Ro.44

SAI 403

AML

FIAT G.50

Macchi C.200


Aviation USK (production ceased)

Caproni Ca.133

FIAT RS.14

IMAM Ro.37

IMAM Ro.43
Savoia Marchetti SM.82

Savoia Marchetti SM.84


AZ Models

Breda Ba.27

Breda Ba.65

IMAM Ro.10

Reggiane RE.2005

SAI 207
SAI 403


Broplan (vac form)
Cant Z.1007 Asso
Caproni Ca.111
Caproni Ca.316
Macchi C.94
Macchi C.100
Savoia Marchetti S.74
Savoia Marchetti SM.75
Savoia Marchetti SM.87
Umbra T-18


Classic Airframe (production ceased)

FIAT Cr.32

FIAT Cr.42

FIAT Br.20

IMAM Ro.37

Reggiane RE.2000

Reggiane RE.2001

Savio Marchetti S.79


Delta2 (production ceased)
Caproni Campini

Macchi C.205

Macchi MC.72

Savoia S.55X


Flashback (Classic Airframe re-issue)

FIAT Cr.42

Savoia Marchetti S.79


FLY Models

SVA 5

Caproni Ca.101


Flying Machines

FIAT G.50

FIAT G.55

Macchi C.200

Piaggio P.108

Reggiane RE.2005


Hasegawa

FIAT G.50

Macchi C.202

Macchi C.205


Italeri

Cant Z.501

Caproni Ca.311

Caproni Ca.313/314

FIAT Br.20
FIAT Cr.42
Macchi C.200
Macchi C.202
Macchi C.205
Reggiane RE.2000
Reggiane RE.2002
Savoia Marchetti S.79

Savoia Marchetti SM.81
Savoia Marchetti SM.82


Jach

SAIMAN 200


Special Hobby (also MPM & Azur)
Breda Ba.65
Breda Ba.88
Caproni Ca.310
FIAT Br.20
FIAT Cr.25
FIAT G.50
FIAT G.55
FIAT G.56

IMAM Ro.43

IMAM Ro.44
IMAM Ro.37
IMAM Ro.57
Macchi C.200
Nardi FN.305
Piaggio P.108
Reggiane RE.2000
Reggiane RE.2003


Pacific Coast Models

FIAT G.55

Macchi C.200

Macchi C.202

Macchi C.205

Reggiane RE.2005


Pavla

FIAT  Cr.42

IMAM Ro.43

IMAM Ro.44

Reggiane RE.2005


RS Models

Avia FL.3

Reggiane RE.2003
Reggiane RE.2005
Reggiane RE.2006

SAI 207


SMER

FIAT Cr.32

FIAT Cr.42

FIAT G.55

Macchi C.200
Macchi MC.72


Supermodel (now part of Italeri)

Cant Z.506B

Cant Z.1007

FIAT Cr.32

FIAT G.55

Reggiane RE.2000

Reggiane RE.2001

Reggiane RE.2002

Savoia Marchetti SM.81


Sweet (1/144 scale)

Macchi C.200


Sword

Reggiane RE.2001

Reggiane RE.2002

Reggiane RE.2005

FIAT G.55 (double kit)


Valom

Caproni Campini

LIMITED RUN RESIN

Aerodim (production ceased)

Breda Ba.25

FIAT G.12


Alitaliane (production ceased)

Macchi M.39

Macchi M.52

Macchi MC.72

Piaggio Pegna PC.7

Reggiane RE.2000

Reggiane RE.2001

Savoia Marchetti SM.84

Savoia Marchetti SM.85


Aerotech

Macchi M.39

Macchi M.52

Macchi MC.72

Piaggio Pegna PC.7


Alphaflight (production ceased)

Cant Z.506B

Cant Z.1007bis

Caproni Vizzola F.5

FIAT Br.20


Astrokit (production ceased)

Macchi C.200


Brach Models (production ceased)

Caproni Ca.116 1/48

Macchi M.33  1/32

Macchi MC.72 1/32


Choroszy Modelbud
Breda Ba.19
Breda Ba.25
Breda Ba.27
Breda Ba.39
Breda Ba.64
Cant Z.504
Caproni Ca.100
Caproni Ca.164
FIAT Br.1
FIAT Cr.20
FIAT G.8
FIAT G.5
Piero Magni PM1
Piero Magni PM2
Piero Magni 3/1
Piero Magni 3/4
SAIMAN 200
Savioa Marchetti SM.78


Craftworks (production ceased)

Macchi C.200

Macchi C.202/5


Cunarmodels (issued by Italiankits)

Caproni Ca.135

Macchi C.207

SAI Ambrosini SS4


Dujin (production ceased)

Breda Ba.33

Caproni Stipa

Caproni CH.1


E.P. Originals (production ceased)

Reggiane RE.2001

Reggiane RE.2002

Savoia Marchetti S.79


Italian Classic (production ceased)

FIAT G.50

Macchi C.200

Reggaine RE.2000


Italiankits

FIAT G.18

FIAT G.50V
FIAT G.55

IMAM Ro.1

Savoia Marchetti SM.89


Italian Wings (production ceased)

Piaggio P.119

Reggiane RE.2004


Karaya

Savoia Marchetti S.65


Kora

Aeronautica Lombarda AR


Legato (production ceased)

Cansa FC20bis

Cant Z.1018

Nardi FN.305

Savoia Marchetti SM.93


Lilium (?) (production ceased)

IMAM Ro.43


LF Models

Ansaldo AC.3

Aeronautica Lombarda AR

Caproni AP.1

Caproni Ca.331

Caproni Vizzola F.4

Caproni Vizzola F.6M

Caproni Vizzola F.6MZ

FIAT G.56
Macchi C.201

Nardi FN.305

Nardi FN.315

Nardi FN.316

Piaggio P.32 I

Piaggio P.32 II

Reggiane RE.2005

SAI Ambrosini 207

Savoia Marchetti SM.86

Savoia Marchetti SM.86W


Massimodel

FIAT CMASA RS-14

IMAM Ro.44


Museum (production ceased)

IMAM Ro.57

FIATCr.32


NOIX Models (production ceased)

FIAT C.29

Macchi M.33

Macchi M.52R

Macchi MC.72

Piaggio Pegna PC.7


Omega Models

Caproni Ca.335
Caproni Ca.355

IMAM Ro.51


Planet Models

Aeronautica Lombarda AR

Breda Ba.44

CANSA FC.20bis

CANSA FC.20ter
Caproni Ca.113


RCR (re-issued by Italiankits)

Breda Ba.65

Caproni Ca.101

FIAT Cr.25
IMAM Ro.37

Savoia Marchetti SM.85


Sem Models
CANSA FC.12
CNA PM.1

IMAM Ro.63

Reggiane RE.2006


Silver Wings

FIAT Cr.32

FIAT Cr.42
Reggiane RE.2000


Vintage (production ceased)

Fiat G.55

IMAM Ro.57

Macchi MC.72

Piaggio Pegna PC.7

Savoia Marchetti S.79