Single Ended Precision Variable Amplitude Square Waves and Charge Injection
I did manage to find a good low charge injection analog switch, and it is about 1/3 the cost of the Linear Tech part.  The LTC part probably has better specs, but they aren't really needed in my design.  Analog Devices has a good article that discusses charge injection on page 22 page of this issue of Analog Dialogue.   It turns out that a key indicator of low charge injection is high switch resistance.  It makes sense because charge injection is proportional to gate area, and lower resistance requires more gate area.  My design can tolerate the higher switch resistance in order to avoid the spikes caused by the charge injection.