Mini IQ (fellow minder had a partyplan thingy), not sure how you get hold of them - someone will be able to tell you soon!)- got some brilliant fun books on basic signing, including board books; lift-the-flap books on different beliefs and people.
Lots of books from Amazon (Boots for a Bridesmaid, Don't Call Me Special, Rainbow Joe and Me, Mama Zoom etc).
Have got proper Makaton sign manual (needed for signing child I mind with DS) - all the children love looking at it.
I bought the Happy Street hospital purely because it had a child in a wheelchair and a pregnant lady in it (didn't think the hospital worth the money!)
Don't ELC do "ethnic" family for their doll's house?
I think you can buy "play" wheelchairs and dolls (nurseries have them?) but I won't on principle because a wheelchair-using friend of mine thinks it's appalling that her lifeline to the outside world should be thought of as a toy. There's a new thread to start ... can't wait for my discussion with inspector at my next OFSTED visit!
A lot of my stuff has been picked up in craft fairs, little shops tucked away in backstreets, and catalogues usually designated for nurseries (eg. multi-cultural cooking equipment)