That is what I did.
1st 70-300 mm VR
2nd 80-200mm F2.8 Af-D
3rd 80-200mm F2.8 AF-s
finally got the 70-200mm VR II.
By the way, I don't think 70-200mm F4 + 1.4x is a good idea. Please do not go F4 + 2X.
I persoanlly struggles now for tele. This is not cheap way, $10 per mm seems is the rule.