They have Ork Bikes, the Warboss on the bike is freaking awesome, but very expensive. I am pretty sure they don't have Space Marine Bikes. Besides, you can just buy a Ravenwing Battleforce and take all the Dark Angel stuff off.
The Grot tanks are really sweet, most of them look like French WWI tanks (Renault FT-17's). I look forward to putting them together.
Hey, you could always get some Ork Bikes and put Space Marines on them. I actually thought about doing the reverse to make a couple of Ork Bikers.