Here's a pair of Fox MTB knee/shin pads for $70

FOX Launch Knee/Shin Pad (Black, Large/X-Large) https://www.amazon.com/dp/B0013NGQ8I/ref=cm_sw_r_cp_api_vhyOybE37ZF38

In my club, a lot of us wear motocross shin guards like these. You get knee protection too and they seem to do the trick well. https://www.amazon.com/dp/B0013NGQ8I?ref=yo_pop_ma_swf