I just got my Softrock Lite II 30m reciever kit this past week and have been assembling it. These kits are phenomenal in several ways - they're extraordinarily well built, they're very inexpensive (my receiver kit was around $20 shipped!), and documentation is very thorough, complete with full step-by-step guides, photos and even soldering tips for beginner kit builders!
The kits are put together by Tony Parks, KB9YIG: http://www.kb9yig.com/
His kits are put together for the love of kit building, and his dedication to his product shows.
As such, the kits are often out of stock but they are usually available on his Tony's website with fairly quick turn around time.
They provide an excellent venture into the world of Software Defined Radios for those who want to explore it without forking over hundreds of dollars. They work by using the computer's soundcard frequency sampling rate and base it around a crystal. With my 48khz soundcard I can get coverage from about 10.100 to 10.148mhz.