I tend to do a box of homemade cakes for the staffroom and then a card written by ds - which is really special as they all know how much he hates writing anything.
Ds has, in the past, made his favourite teachers and TAs hamma bead hearts, which we string for hanging and again, these were appreciated, because they know he has fine motor issues, so had worked really hard on them. One teacher in particular made a point of finding him to tell her how special it was to her and how she keeps it hanging on her dressing table mirror. 
Prior to our SEN days, I used to buy Molten Brown stuff in the sales and give them that, as I figured even if they didn't like the scent at least it would be something nice for re-gifting! 
Last year all the boys' teachers got hand decorated cupcakes dressed up in a nice box along with a card from him and a note from us.
This year I have bought ds1's teacher a piece of jewellery, as she has been fantastic with him from start to finish. Ds wanted to give her something relating to her hobby and I had noticed she wears this type of jewellery regularly, so we put our heads together and came up with something that encompassed both. (Ds's first idea would have cost a couple of hundred pounds!
)
Need an idea for his lovely, lovely maths teacher now, as she has been instrumental in rebuilding his confidence from zero to happy and loving maths again. Bit stuck on that one at the moment.