I thought about lights too but couldn't do it because of the nasty color coming out of those little tubes. Then went the big handle mount flash route (the big Canon ones) and fun with umbrellas and cheap light stands and now I am where Parker has suggested.....studio flash. It has taken me close to two months to get together 2 White Lightning x1600s and 2 Alien Bee B800s. Just keep looking, you WILL find the deals on them, it will take some time though. Honestly, and I hate to say this, but the guys at Fred Miranda always have someone dumping Bees or Lightnings. Look here and there.....something will pop up.
I will never, ever use another camera mounted speed lite for any planned photo event at the house again. It is to easy to pull out one studio flash and a reflector, 10 minutes or less I am ready for an exceptional photo, not half assed like the used to be. You haven't said what or why you wanted better portrait shots, I am assuming you are doing them around the house.....don't cheap this one out, the results are exponentially better. Buy the time you screw around building and buying crap, you will be within range of a studio strobe. I would suggest a Alien Bee 800, but if you are strapped. Start with a B400 and a reflector and you will be set for most indoor stuff for now.....but get the 800 if you can swing it....or more.
Don't do like I have done and waste alot of money chasing around different flashes for nothing when all you need to do is get a good studio flash.......why I didn't do it before leaves me wondering what the heck I was thinking. However, the big handle mount flashes do look cool when arriving at an event.....not many people are crazy enough to still use them and those darn new cameras with crazy ISO spoil all the fun.