Good, I got to jump in before the master of plasticard popped in (OD from TV) an put in my two teef worth.
I have been playing orks since the Armageddon days, and have had to "scratch build" ie LOOT many models and adapt them to orkisness. That is the main reason I switched from eldar to orks is the modeling fun and challenge.
In those days there were not even battle wagon models so I got to make my own BWs out of other companies models, just glue/pin some GW parts on there and presto; an ork model that was legal even at tourney.
The only models that were off limits were the boys, and since they had boxes of plastic boys come out that was no problem to just buy more boys and use the spare parts for other kit bashing to make more ork stuff.
Then when IA8 came out out, a new wave of kit bashing came out, love my junkas!
That is probably the main reason I stay an ork, is the endless looting potential, and kit bashing that I get to do. The cooler the model the less objectionable to other players.
For example here is a picture of my Gork Rider, (with a Deff copta for size comparison) That I use as the boss from IA8.
click on the picture for full size
The kit bashing/looting is what sets the orks apart from the other armies in this game. The orks can almost make anything out of other parts and it is legal to use in a game. The great "counts as" clause makes orks a hoot to play.
So, if GW can't keep up with the demand for models just make your own.
My Two Teef