Fanny, I have a mix of Alien Bees and the White Lightening flashes. Honestly I prefer using my White Lightening X1600s indoors. If I want/need a hair light I will use my Alien Bee B800s on a boom for effect. I am fairly new to studio lighting too. Got a couple of PLMs and life is good as I learn more and more everytime I use them.
I have some new and some used. Look around, if used is close to new, I recommend new for the warrantee and when you put together a "deal", it may be better than used. I got my stuff over three years ago and took a long time to find the "right" deal. As I recall I bought one Alien Bee and then used the increasing discount to add on multiple stands, PLMs and modifiers I thought I would need. If you are serious, join Buff's forum and read, read, read and ask specific questions.......make sure and mention exactly how you are going to use them. That will assist the forum with specific recommendations.