A part from Ennio Morricone, there are some other interesting composers for Italo-Western film scores.Nowadays it is quite difficult to find these soundtracks. It is hard to find Morricone's lesser known (often brillant) scores too,  because the film wasn't succesful. Here is a list of my favorite film composers and my favourite scores. 

Riz Ortolani : La notte dei serpenti '69

Luis Bacalov : the grand duel (Quarantino used a track of the film for Kill Bill)

Angelo F. Lavagnino :uno straniero a Paso Bravo'67/ Requiem por un gringo'67

Augusto Martelli : Ancora dollari per i Mc Gregor '70

Vince Tempera :Carambola '74 / Sella d'argento '78

Carlo Rustichelli : I quatro dell 'ave maria '68

Franzesco di Masi :Quanto costa morire '68

Pino Donaggio :Amore, piombo e furore '78

Gianni Ferrio : Los Despoerados '69 /Amico stammi lontano almeno un palmo '73

Roberto Pregadio : Deserto di fuocco'70

and some  lesser known Morricone soundtracks: 

il mercenario '71 (Quarantino used a track of the film for Kill Bill)/Giu la testa'71/

 Ochio alla penna '81

and a special mention  for Edda dell'Orso the vocalist who has become famous for her high pitched vocalizes in Leone's 'Once upon a time 'and who is to be heard in many other scores. There are two interesting CD compilations : 'Spaghetti Western' Vol 1 & 2 (4Cd's) On DRG, and a 2Cd set with Morricone Western Scores 'The Western' on RCA which is not easy to find.