Although we're guessing that cheap is a relative term.
Japanese BMW tuner 3D Design have just announced a whole new line of products for the X4 which can be purchased individually or as a set. Most of this consists of aero bits, although there is also the option for new wheels and a few interior pieces. There is a new front splitter, which will require that you also also purchase the M Sport package from BMW, although this is the only part of the kit that demands such a requirement.
For the roof and trunk spoiler, you have a choice of urethane or carbon fiber, which is always nice to have. Of course, this isn't an option for everything, and if you opt for the new rear diffuser, you'll have to have carbon fiber. It does look good though, especially with the new exhaust tips. There is a coilover package which will lower the vehicle by 30 mm, rounding out the exterior modifications. On the inside there are some new carbon-fiber trim options, which are fine, but also offered is a new set of pedals and floor mats with the 3D Design logo on them. We're not crazy about that list part, but it's not really such a big deal.