According to SweClockers custom Radeon R9 290X graphics cards will not be available sooner than the end of fourth quarter of this year.
Manufacturers usually need four to six weeks to deliver custom cards to the market. For that reason SweClockers assume that custom models can even be delayed till December (sounds too dramatic though). According to their sources AMD has not yet delivered enough Hawaii GPUs units to AIBs, so they are not prepared for mass production. That said, if you were going to purchase the R9 290X, you have two options: wait for better coolers or buy a cheapest reference model you can find and install aftermarket cooler on your own. Some etailers, like OCUK, already offer custom solutions (pictures above).
ComputerBase confirmed that Prolimatech MK-26 and Arctics Accelero Xtreme III and Accelero Hybrid already support R9 290X, so if you are really desperate for lower temperatures and quieter operation this is probably the best way to go.