01 Smokescreen - WRC WRX STi
02 Sideswipe - 04 Viper (red)
03 Silverstreak - 04 WRX (silver)
04 Hound - Jeep (green)
05 Tracks - 04 Vette (blue)
06 Dead End - 04 Viper GTS (black)
07 Meister (Jazz) - 04 RX-8(white)
08 Swindle - 04 Jeep (yellow)
09 Grimlock - 05 Mustang (silver)
10 Windcharger - 05 S2000 (red)
11 Battle Ravage - 04 Vette (black)
12 Shockblast - 04 RX-8 (purple)
13 Wheeljack - 05 Mustang (white)
14 Decepticharge - 05 S2000 (yellow) *new, never seen yet
15 Swerve - 04 Vette (red)
16 Prowl - 05 RSX (patroll version) *new, never seen yet

What you have:
01 Smokescreen - WRC WRX STi
12 Shockblast - 04 RX-8 (purple)
15 Swerve - 04 Vette (red)

What you won't see:
04 Hound - Jeep (green)
05 Tracks - 04 Vette (blue)
06 Dead End - 04 Viper GTS (black)
07 Meister (Jazz) - 04 RX-8(white)

What you should jump on:
14 Decepticharge - 05 S2000 (yellow) *new, never seen yet
15 Swerve - 04 Vette (red)
16 Prowl - 05 RSX (patroll version) *new, never seen yet

What you should buy next (in order):
13 Wheeljack - 05 Mustang (white)
10 Windcharger - 05 S2000 (red)
11 Battle Ravage - 04 Vette (black)
09 Grimlock - 05 Mustang (silver)
03 Silverstreak - 04 WRX (silver)
02 Sideswipe - 04 Viper (red)
08 Swindle - 04 Jeep (yellow)

This is based off of difficulty to find.