The Entertainer now sells One Step Changers such as Rollbar, Megatron, Prowl & Strafe for £5.00 each as well as some of the others.
They also have the Dlx Silver Knight Optimus and Voyager (chrome) FOC Grimlock set for £17.49.
If you have any interest in Movie toys at all Megatron is actually pretty good - his vehicle mode is one of the best representations of the character I've seen to date. only the Stealthforce one beats it and it's a heck of a lot better than the FAB ROTF Megatron.
Prowl is a curiosity as he's 'very' IDW like. Rollbar is OK not great but OK - looks nice just standing and the car is not to bad. Strafe is actually pretty clever and has decent joints in the wings and even has movable knees and arms.
As for the othersGalvatron is OK, Heli-Drift I quite like - he's fun to mess with - Steeljaw is decent his articulation is a bit odd but he has the over all effect of the characters type... He's interesting I guess as he is a Transformer that likely isn't a Transformer (like Alpha Q was).