I am looking for some advice and know this is the place to go for level headed responses.....

I am trying to spend as much time as possible concentrating on wildlife photography but am finding it difficult to get results on anything other than common garden birds and captive animals. This is mainly due to me being 'larger than the average bear' (height wise although the trousers do seem to be getting tighter lately!) and therefore not overly blessed with stealth. In my mind the alternative is to go for longer range lenses (I'm currently using a Sigma 70-300 telephoto on a Nikon F80) but the credit card shrunk at the sight of the price tags.

I've done the usual trawling through Ebay but still cannot find anything that falls into a reasonable range. Has anyone got any tips or tricks for overcoming this ?? I've looked at hides but most of the photography is to be done on common land so poses the obvious threat of removal by our light fingered friends. What are peoples thoughts on teleconvertors ??

Thanks in advance for your help.

Olly