The Synergy albums were released starting in the mid 1970s, with the last album released in 1986. The vinyls are of course long out of print, and the CDs also pressed by the defunct label Passport Records are approaching collector's item status. Even so, many record stores that deal in used vinyls and CDs still have Synergy albums lurking in their inventories.
Fast created the subsidiary label Audion Recording Co. under Passport records as a base for new composers to make their music available. There are several good musicians from this brief time; if you find any CDs bearing the Audion label, it is probably worth picking up. Some Synergy appears on the Audion Sampler CD.
I might note that one other LP (now available as a CD) has an excerpt from Legacy (my favorite Synergy track), but the CD is well worth getting for the other music too. It has several Vangelis' tracks, including excerpts from Heaven & Hell and Alpha as well as some Tomita and the incredible opening to the late, great blues guitarist Roy Buchanan's Fly Night Bird. That disc is The Music of Cosmos, from the late 1970s space science series hosted by Carl Sagan.
Title, Year, LP/CD Cat.#, Crow has:
Electronic Realizations for Rock Orchestra, 1975, PB[CD]-6001, LP & CD
Sequencer, 1976, PB[CD]-6002, LP
Cords, 1979, PB[CD]-6000, LP & CD
Games, 1979, PB[CD]-6003, LP & CD
Audion, 1981, PB[CD]-6005, LP & CD
The Jupiter Menace: OST (CD never released) 1982, PB-6014, LP
Semi-Conductor (two LP w/tracks from above) 1984, PB-11002, LP
Computer Experiments Vol.1 (limited ed. LP) 1981, SYNCD-104, LP #3399
Metropolitan Suite, 1986, SYNCD-204, CD
Audion Sampler, First Edition, 1986, SYNCD-105, CD
The Music of Cosmos (LP released in 1981), 1994, 07863540032, LP & CD