I wanted to get a telephoto lens for my Sony A7Rii and found this very interesting option:
A 1961 LEICA ELMAR 135mm f/4 (39mm filters, 14.3 oz./405g)
I found it on eBay for around $200 and based on the review here it sounded like a fantastic lens to use for sports photography and nature shots. So far, I like it a lot. You have to respect a lens when it is older than you and still shoots this well...