We have good news for affordable scientific computing on GPUs. Even though the AMD R9-290X made a step back by reducing double precision performance to 1/8 of single precision performance, this proved the R9-280X (with 1/4 dp to sp ratio) a true bargain for a ~1TFLOPS double precision performer for just $300. Furthermore, NVidia's upcomming GTX-780Ti GPU is rumored to have unlocked double precision units* turning it to a true number cruncher (more than 1.5 TFLOPS in dp compute) for a respectable $699, which is much less than GTX-Titan's price though.
Update: Unfortunately, it seems that the DP compute capability of GTX 780Ti is controversial. According to other information**, which seems valid, the DP potential is still limited to 1/24 of SP. This proves the first link bellow inaccurate. Too bad for low budget researchers!
Sources:
*: http://videocardz.com/47576/nvidia-geforce-gtx-780-ti-official-specifications
**: http://www.tomshardware.com/reviews/geforce-gtx-780-ti-review-benchmarks,3663.html#xtor=RSS-182
