Yesterday I was reading through Professional Photographer and came upon an article by Damon Tucci that reminded me how a little light can give you some pretty dramatic results.
Take one single Speedlight (or Speedlite) a little off camera and look what happens.
A Speedlight is a powerful tool, all you need to do is watch Zack Arias OneLight DVD to see the many things that one light can do. Throw a simple inexpensive Speedlight softbox into the mix and the sky is the limit.
There is no substitute for the the right knowledge and correct tools and it won't cost you an arm and a leg: the OneLight DVD ($150), a hotshoe flash ($99), softbox ($34), shoot through umbrella ($25), cactus triggers ($50) or flash cord ($25), and a light stand ($20) will cost you around $350.
You can do it for less by sharing the cost of the DVD's with a friend, or don't buy the DVD's and use the thousands of free photography educational resources on the web. The prices I quoted is for new gear so you could save even more money buying used.
So I hope I have eliminated all the reasons why you thought you couldn't do it.
Go check out the Damon Tucci article for for the details on how he shot the above images, and be sure to check out his website as well. If you are are going to Imaging USA this coming January you should sign up for his course.