I guess I should mention what I'm using them for! It'll be mostly shoots involving 1, occasionally 2 people until I have a better grasp of lighting and some still life stuff. I was thinking about starting with one head in the range 400-600W/s to start with from a well-regarded manufacture so that any accessories I buy will fit other heads I eventually get. I'll probably spring for a power pack at some point but I have a pretty tight budget so all of my shooting will be in my home or at someone else's. It's pretty bewildering looking through all the choices at the multi-manufacturer online catalog of B&H! I definitely have a lot of research to do.
tomalphicon, is that the Fuji Instax stuff and the RB Polaroid backs that take the 100 and 600 series film? That would great, it's a LOT cheaper than the impossibleproject film!