Our dissection room staff told me that Waterstones in Gower Street sold them. We went to have a look and they were about £250. I couldn't really speak for their quality (they are plastic) as we were only in our second term when we were examining them but we were impressed at the time.
They were way beyond our price bracket (we were looking to buy a skeleton as a birthday present for a fellow student but sadly she declined as we had been very much looking forward to wheeling it into her party which was full of City people )
Interestingly mine was acquired from Adams&Rouiley (according to the box anyway) by one of my great grandparents. Its been to medschool each generation since. Though the Skull does look like someone wanted the subject to supply a child sized skeleton but didn't quite hit them hard enough.
The DR room at manchester has tons of real skeletons hnaging around, you can just pop on when you want to look at them and we also use them during the DR sessions, along with the bodies, prosections and disartiulated bones (we also have some elephant bones which are cool). We also have 10 full disarticulated ones (real) in the medics lib that you can borrown for a few hours at a time. - I have not come across a skeleton that was not real while i have been here.
I have not seen the need to buy my own, I am happy using the ones provided for us, and the antomy resource area is open every day here, and it is never overly busy.