I've found that on eBay:

http://cgi.ebay.fr/45T-GHOSTBUSTERS-SOS-Fantomes-Teddy-Mc-DONALD-1984_W0QQitemZ400046123426QQcmdZViewItemQQimsxZ20090427?IMSfp=TL0904271310002r5315


Does anyone know what could it be? I know it's the song but I've never heard of it…

think it's just another cover of the Ray Parker Jr. song. (i know everyone probably guessed that, but I had a brief hope that it could have been a very rare copy of the “original” ghostbusters song used in the trailer. man how I wish we could find that thing.)

and by my google powers (yes, i'm googleman! ahem) i've a feeling it's an electro/funk style version.

http://www.discogs.com/Teddy-Mc-Donald-Ghostbusters-Theme-Principal-Du-Film-SOS-Fantomes/release/1368330