at first I thought speedlites (that's what the term 'strobist' usually refers to these days, not just people using strobes), but that might not be that much cheaper.
If you're outside, I would definitely recommend looking into a nice stand and reflector-holder or two. You can use these to hold up several types of reflectors and natural light modifiers. I've found that even in direct sun you can get nice, soft light if you use a diffuser like this.
for really cheap 'artificial' lighting you could buy some cheap flood lights from home depot or lowes.
for cheap (but decent quality) strobes check out alienbees.com. They're not the top quality, but I must admit their light quality is very good and in my experiences extremely reliable. Some claim that they have exposure and white balance issues and are inconsistent, but I have NEVER had these problems with mine.