Do you need high speed sync? trailing-curtain sync? p-TTL remote triggering? modelling light?
If none of the above, you can get away with something like a Pentax AF280T, Sunpak 383, 444D, 36DX, 422D, 30DX, Vivitar 5600, 4600, 5200, 3700. They cost almost nothing, OK, not nothing, but less than USD 50 for sure.
For more power and features (mainly zoom head, more power ratio settings in manual mode, more aperture settings in auto mode), get a Nikon SB-24, 25, 26, 28, or Contax TLA 360 for less than USD 100.
My favorite is Metz 54MZ3/4/4-i with SCA3702, but they are pretty rare and if found, cost more.
My most-used setup for indoor shooting is a Metz 54MZ4 with SCA3702 on camera, with light bouncing, and a remote-triggered Metz 54MZ4 with SCA3083 to augment ambient light.
Just don't buy a flash without bounce&swivel head, or with p-TTL mode only. You'll regret later.
Edited:
Just re-read your post, and noticed this:
Originally posted by Biro gala events in grand ballrooms of major hotels.
You should try something like a Quantum Qflash or a Sunpak 120J. Bare bulb is great for large ballrooms.
A decent used outfit, including a high voltage external power pack, is about the price of a new Pentax AF540FGZ. From KEH, I bought a Sunpak 120J TTL and a Lumedyne Microcycler (both EX grade) for
less than the going price of a
used AF540FGZ.
Last edited by SOldBear; 11-17-2012 at 05:38 PM.