Hi!
I understand your frustration over the cooker. I am in absolutely identical situation at the moment. Ironically things did not change much since March. The only available suitable cooker (which is 60cm wide) is Canon Chesterfield - and - yes, it is still �600. The other one I considered was Indesit KD6G25, but it is almost just as expensive. Oh, yeah - and the third one is also Canon - C367GX. There are cheaper ones of course, but although their are compliant, the are all 50cm wide, as I am sure you had already found out.
The retailers were slow to catch up, so they are allowed to sell the uncompliant gas cookers for a bit longer. Many of them are still ignorant.
I wonder what you decided to do in the end. I am seriously considering buying a second-hand electric cooker, since electric ones are also very expensive new and since you end up paying more for the electricity then gas in the long run, you want to buy the electric one for as cheap as possible.
The whole state of things is extremely dissappointing. This new regulation made my life so much harder!