Sigma has 120-400/4.5-5.6, 150-500/5-6.3 and 50-500/4.5-6.3 at resonable prices.
Tamron has a 200-500/5-6.3.
Tokina has 80-400/4.5-5.6.
However I guess non of them are close to Canons affordable telephoto lenses such as:
400/5.6, 100-400/4.5-5.6 and 300/4 + 1.4x Ext.
Most mm for the money are the sigma 15+-500mm zoom lenses.
A camera, a lense and a tripod.