@kennyR
http://www.ramseyelectronics.com/cgi-bin/commerce.exe?keywords=mixer&defaction=search&y=Ramsey makes a mixer kit $49.00 two stereo line and one phono which you can easily convert into another stereo line input, stereo mic input and headphone out and line out.
the mic input can be converted or you can simply build or buy yourself a 10:1 padded cable to convert line level to mic. Real simple even if you are inexperienced with a soldering iron should not take you no more than three hours to put together.
All you need to construct a padded cable is a cable and four resistors two 4.7k and two 47k.
cut the cable in half put the 47k in the audio path and the 4.7k from the audio to gnd on the line side of the 47k resistor.
If you need additional help in the construction of a padded cable I can draw you a picture.
That should give you what you need without any design headaches or big price tag.
