Though not all go on sale. Most of my gucci collection never went on sale and I purchased them at retail price. All but one are no longer available/produced. So it really depends on the piece a customer is looking for.
jroger: if it's a seasonal bag, you can wait and see if you want to try to wait for a sale. Usually seasonal items go on sale unless if the item is really popular and is sold out before making the sale. Btw, what bag are you thinking about?
The Jungle Zip Hobo (some call it small, others call it medium) in Beige, not sure of the official name. I've seen it commonly in black and white, but not beige of course that is what I want. Gucci said it is discontinued, I believe it's from 2010 and I just missed it in the Dec 2011 sale. I do not get a chance to shop at the stores, just online which puts me at a huge disadvantage.
http://www.saksfifthavenue.com/main/ProductDetail.jsp?PRODUCT<>prd_id=845524446245182