Well initially I was budgeting money towards getting an Autocom system now since the colder months are setting in I'm realizing staying warm might be much more important than listening to all of my 80's metal mix tapes

I have a pair of motorcycle pants I love to wear. However they are made for the warmer months as they have lots of breathable layers. I was looking for something I could wear underneath it and I wanted to know if anyone had any recommendations?
As a side note hunting/trail riding/and other such outdoor activities are not too big in my neck of the woods. So there aren't too many local experts/shops I could go to so if anyone has any suggestions. If possible I'd appreciate any recommendations be something I could purchase online.