The Corpus Scriptorum Christianorum Orientalium is perhaps the main series of modern editions of oriental writers in Syriac, Ethiopic, etc. Few will be aware that all of the volumes seem to be in print. It seems that they can be ordered from Peeters of Leuven. A list of all volumes is here. However the listings are very brief, and it would probably be a good idea to check against the listings in COPAC before ordering. Volumes were often issued in fascicles, and most texts consist of two volumes, one in Syriac and the other in translation. Originally the translations were all in Latin, but in the last few decadent decades, mainstream modern languages have been used instead. The prices are really very cheap, and I might have a go at one or two and see how it works.