I have the Horseware ones, slightly lined, size XL - I am a sixe 16 (ish!!) think they cost about £35 - don't know if they're breathable but guess so, they keep you dry and warm and you can ride in them.
I have got a Horseware pair - they are good and also a pair of Joules ones. Not sure if they do them this year though. They were a sale bargain last year!
As already said Horseware/Rambo ones are great, I have the chaps not the trousers but my sister has the full trousers and I am sure they do large enough sizes, we got the non-lined trousers and chaps as a bit more lightweight.
My lovely father has just bought me some new waterproofs for work, from a company that make them for trawlermen etc. They are breathable, dont rip and flexible (kind of stretchy material) and cheap! He swears by them...cant remember the name off the top of my head but can find out for you?
I did see somewhere on ebay that do made to measure, have a look on there think it was a company in Surrey?? Reasonably priced. I have Rambo ones size L I am a 14 but think after Xmas excesses i need to lose some weight as they were a bit snug round the bum last week!! oops!