im thinking of getting an obitsu but i dont very much about them.
whats the cheapest way to get them?
are they hard to put together?
and anything else i should know about them

I don't know much about Obitsu dolls myself, but I buy the 27cm bodies for my Pullips

Here's all I can tell you...
There are different kind of bodies, if you are looking into the 1/6 scaled (barbie sized) dolls, they're quite affordable. The 55cm (I think it was 55cm... Or 60cm?) Obitsus are a bit more pricey, I've heard just the bodies range in the $100-200s.
I think it shouldn't be too hard to put together the 1/6 dolls. I think their heads are soft (like Barbie's) so you could just pop it onto the body. I might be wrong, as I've never seen an Obitsu head.
The bodies all (except the 27cm female ones) come with spare hands, you can just pull the hand out and stick the alternatie hands inside. (Like Pinky heads )
They sell decals of eyes which you can just stick onto the faces or you can buy paints to paint your own face.

Finally where to buy:
I usually buy my Obitsus from www.mimiwoo.com (they're in HK and very reliable!) or you can order them from www.junkyspot.com (they're in the US)
They also sell ready made dolls, which cost a bit more (maybe around $60-80) the variety isn't that big though and I think it might be cheaper to actually buy the parts and make your own.

I'm sorry if I'm not much of a help here.

thanks