Hobbylab has a pretty nice looking PC USB Oscilloscope for $170 –

PC USB Oscilloscope is a great tool for your microcontroller projects! Simply connect the device to the computer USB port, run the Windows application and you can analyze the UART, SPI, I2C and 1-Wire interface signals. In the same box you get Oscilloscope, Logic analyzer, Spectrum analyzer, Recorder and Logic generator with a lot of potentialities for the affordable price!

PC USB Oscilloscope / UART, SPI, I2C, 1-Wire Logic Analyzer. Great for PIC and AVR projects! –Link.