Ok- I am looking to purchase a speedlight. I know the SB-28 is the top of the line but what is the best speedlight for the money and how much should I expect to pay? I have been looking on ebay and it looks as if there are so many models from which to choose.
For wildlife I would think GN is everything, as you (I assume) need the power to reach a subject that is not exactly sitting next to you. You should probably bite the bullet and go for the SB28, as it is the most powerful flash Nikon offers. I love my SB50, but I don't think it would provide enough light for your particular application.
Nikonian in the High Desert of Southern California.
Depending on whether you wanted to purchase new or used, I'd recommend putting some money on a high end flash.
New: SB-28 or SB-27 Used: SB-24, -25, -26, -27, -28
Why? High guide number will ensure that you have the reach that you want when taking pictures at a distance. (Remember, light output is halved when distance is doubled.) All of the above models (except the -27) have bounce and swivel heads. The -26, -27, and -28 have red eye reduction for portraits (the -28's red eye mode is set on the camera and cannot be set on the flash). The above speedlights further reduce red eye by increasing the distance between the flash head and lens axis. Also, these flashes have a relatively quick recycle time.
(BTW, I just picked up Thom Hogan's The Nikon Flash Guide (HIGHLY RECOMMENDED FOR ANYONE INTERESTED IN FLASH PHOTOGRAPHY) he uses an SB-27 for outdoor/wildlife pics because it recycles faster than the SB-28, even though it has a lower GN.)
PS You bought a Nikon for a reason. Don't skimp on a quality flash.