Analog buffer without op-amps
One alternative is to build a common collector with a BJT or a common drain with JFET. It works almost as a buffer: high input impedance, low output impedance and almost a unity gain. Being a simple circuit you can implement without problem. JFET produces a better alternative to low input current needed.

 

Common Collector and Common Drain

If you need more inputs/outputs you can use a common collector array chip such as CA3082. It will save you lots of space. Unfortunately I don't know a chip with common drain array built in.