Second-hand Norman portables are usually pretty affordable. The least expensive would be a 200B pack and LH-2 head, but the older batteries may need to be replaced, and it's kind of a heavy pack. The upgrade to new Delta V batteries and charger can be costly, and is worth it in my opinion, but replacements for the old style battery aren't too expensive.
This is a 200B pack hanging on my shoulder and an LH2 head with a tele-reflector and bulb spacer mounted on a Norman bracket. I'm using it as fill in full daylight--
I've since replaced it with a 200C pack, which is smaller and lighter, and I have an 202 AC pack that I use with a pair of these heads on a copy stand, and I've also got an LH-3b head, which uses less power, offers more control of power level, has a swivel head, and has fairly accurate non-ttl auto flash with the range of Norman reflectors.
The 200B & C packs are 200 W-s, and there is a 400B pack, same size as the 200B, which can output 400 W-s.
These were shot on 4x5" with a Norman 200C/LH-2 setup using a plain 5" reflector for a hard Weegee effect--
http://www.echonyc.com/~goldfarb/photo/halloween/index.htm