The fellow is right about equipment cost. I once saw... More to the point, the long telephoto lenses cost a mint of money.
Regarding flash, its range is generally too short (a few meters, at best). Moreover, flash will bring another type of harsh lighting, unless it is used as fill flash, to fill in the shadows. Last, but not least, the photographer's position is critical: maybe on the same level or above the bird. This can be generally accomplished on a cliff (or on a helicopter, which cost more than the expensive lens to begin with). Quite an ambitious project.
Have you thought of starting with Sungei Nature Reserve, for example? Many of the birds are at least standing still, which will allow you to practice. They say this is also the best way to start underwater photography: with a slow-moving sea star, not a fish.
