Perhaps the 400mm 3.5 ED IF AI-S and a modified TC-16A would provide solid IQ with a limited AF. Around $1.200 on eBay plus shipping and duties.
Didn’t try it though, but the 400mm 3.5 was notorious for tolerating TC’s, since the optics are said to be top notch.
However the 200-500mm 5.6E is in that range too, maybe also the Tamron G2 / Sigma Contemporary 150-600mm.
The 200-500mm has too long zoom throw, but one can get used to zoom twisting the body. Tamron and Sigma, may have overall quality or AF issues.