I saved around 13.3 million space credits and spent it all last night on spector packs. I also maxed out (255) my medigel, rockets, ops packs and clip packs so that I get more amps and stuff.
13.3 million gets you 221 spector packs. If I were to buy this many packs with real money it would cost about 443 dollars. I got 14 ultra rare unlocks which is around %6.3. This rate is about what people have been reporting for spector packs.
I also got tons of level 3 and 4 consumbles which was what I wanted although the store was a bit stingy with the shotgun amps. 88 more ultra rare unlocks to go for a maxed manifest. At this rate I should have it just before ME4 launch.