Really tired of people saying they can't take good photos because "their gear isn't good enough" and/or "new/better gear is too expensive".
Yes, the latest and greatest gear on the market is expensive but there is tons of older/ used gear on the market that is absolutely fantastic at a fraction of the cost.
For example I bought my 400 f2.8 AF-S (circa 2000) and 200-400 f4 VR (circa 2004) for $2500 each and they are both absolute tanks and function flawlessly.
Sorry to the Canon shooters out there because I can't help you out. For the Nikon shooters that are looking for longer lenses, if you have a body with a built in AF motor, you can pick up an old school 300 f4D AF lens for under $500 used.
Its a fantastic piece of glass that, despite being an AF lens, does a good job keeping up tracking subjects, is tack sharp, and has great color. You can check out a video I did about it HERE.
Here's one I took the other night with my 10 year old D3 and circa 1999 300 f4D.