Ah nice.
Yea I couldn't even afford the Canon 400mm! I went for a cheap 'Opteka' (nope me either) 100-400mm shipped over from the US.
It's the slowest auto focus EVER (when it works at all)
But I've still managed to get some decent shots with it, usually at 300mm as It's a tad soft at 400mm.
https://www.flickr.com/photos/deke19...57635279643937

Some of the shots I took at Blackpool airshow a few years ago.