Erm, I think the going rate is around £200? I am not sure, may be 10% less to get it sold. I got it around 2007 I recall, I sold off all my EF-S lenses and began building towards EF lens only and it was the first lens that I got. I had it serviced at Canon at Elstree last summer at the cost of £195(!), have the receipt still so the lens is in tip top shape, still have the box and hood (although it has some scuffs on the hood), will come with a Hoya pro-1 UV filter).
I'll list it in MM soon as the Sigma gets a release date, along with my 85/1.8, I've not used that since I got my 85L.