Yep, I have a brown T6 (hard to come by) cob 17" with the two widest gullets. Year old in perfect condition. Cost £425 new, want £310 for it (includes p&p).
I have a brown T4 Cob 17.5 I'm selling. Bought summer 2009, used for around 9 months - excellent condition, interchangable gullet system and fitted with the red one (think that's the narrowest of the 'wide' fittings, still pretty wide though as fitted to a Highland Pony).
It's got a square cantel and very confortable for rider as well. A Master Saddler valued it a couple of weeks ago at £350 (they're £395 new).
Have a brown 18 inch but prob more for WB/TB type,although it is a wide fitting.Only used for a while until WB achieved ideal condition and topline for a jump saddle.It was purchased new and had about 6 months use ans is now sitting very idle on a saddle rack.Would accept £200.
I found my standard T6 on ebay but there are usually a couple of cob ones on there T4 and T6's of various sizes at any one time. I was told there was no second hand market by my saddler as they are 'worth their weight in gold' where they are so interchangeable but i bought mine second hand, but like new for £230 including new stirrups, girth and stirrup leathers so worth taking a look on there