Oh my... I hadn't really looked at those kits until now. I'm surprised by the age of some of the sculpts used (that old Ork warbike, wow).
Anyway, the Raiders box really is actually a pretty good deal - the next step up would have been Warboss Grukk's Boss-Mob (shown below) which is a Warboss and the more modern Nobz kit (more weapons and bitz than the mono-pose 5 from the Raiders box), however even that is a few more quid than the Raiders box, and doesn't come with the paints or Deffcopter etc!
Deffcopters are useful to have and it can be hard to get hold of the plastic ones (which look
way better than the metal
IMO) as they have only been released in the Assault on Black Reach starter set and now this new easy-build set of kits.
The downside will be that the Nobz probably won't see alot of action once your collection expands, but as long as you're ok with that then go for it.
I'm only hoping that the paint pots shown aren't the correct ones, as there's no green paint in any of the Ork box photos!