SDRWishList

Upconverter from MF and HF, 300 KHz - 30 MHz, to 100.5 MHz suitable for RTLSDR or Funcube -
 * http://www.amazon.com/gp/product/B009LQT3G6/ref=as_li_tf_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=B009LQT3G6&linkCode=as2&tag=hamradsci09-20
 * suitable for doing ultrasound imaging. (2-10 MHz)

Get an ubertooth one - http://greatscottgadgets.com/ubertoothone/ - 2.4 GHz software defined transceiver
 * 120$ from (checked just this) http://www.seattletechnicalbooks.com/great-scott-gadgets
 * good for learning bluetooth by implementing Bleutooth Low Energy on the dongle

Another RTLSDR capable dongle, but better:
 * http://www.nooelec.com/store/nooelec-nesdr-nano-sdr-dvb-t-usb-stick-r820t-w-antenna-and-remote-control.html#.Uwu0T2coHbA
 * 20$

BladeRF http://www.nuand.com/
 * 300MHz - 3.8GHz, 12 bit 40 MSPS (28 MHz duplex? doesn't fit)
 * x40 - 420$. 40KLE Cyclone 4 FPGA
 * x115 - 650$. 115KLE Cyclone IV FPGA

hundreds of KHz - 30 MHz with 1.85 MHz bandwidth, 12bit sampler 80 MSPS, < 300$, Israely, network interface. (get an allwinner oliduino, with it)
 * http://www.afedri-sdr.com/

14 bit 525$
 * http://rfspace.com/RFSPACE/SDR-IQ.html

open source, 16 bit 130 MSPS, but less good then the perseus in some reviews, but others like him, 900$
 * http://www.srl-llc.com/

= Not really = FunCubeDonglePro - dongle 192KHz bandwidth from 150KHz to 1.9GHz with a hole around 300 MHz.
 * http://www.funcubedongle.com/?page_id=1201
 * 125 british pound.