Then there are folks like me who seek out vintage glass. Yes some like the 300 F/2.8 or the 400 or 500(drool) or 800mm are indeed expensive but if you don't need that speed there are great buys in prime tele glass. I dig my 300mm f/4.5 ed if, is superb and on a TC-301 I have some long glass. The older Tamron 200-400mm ah ld is super and inexpensive and gives darn good results.Or the 100-300 ai mf lens. Super glass and cheap.They all work on my D7100 and on the F4s I get Matrix. Or the Nikkor 180mm f/2.8 Ai ed . A knock your socks off piece of glass. Put it on a TC-201 and voila! 360 mm of joyful sharpness and colorcast.
Just another way of finding good glass at inexpensive prices.