I need flash ideas (master/slave) for a Nikon D5100, reasonably priced. Any suggestions?

I'm new to the photography world, and need help. I'm looking to do studio/wedding photography eventually. I need something reasonably priced right now, will upgrade after time. Not really sure which flashes (master/slave) are good. Any suggestions would be great!

The Nikon CLS system is a great flash system and is included on the SB600, SB700, SB800. SB900, and SB910. Among other things, this includes a wireless remote connectivity feature so the camera can control the flashes wirelessly.

However, you can't use any of these flashes for wireless remote as your camera, being entry level, does not have remote commander functionality.

However, you can buy a SU800 - which is a remote commander for these flashes so that you can control them wirelessly via the camera. The SU800 plugs on top of the hot shoe on the camera.