My memory isn't what is used to be , but I seem to remember a friend picking up a complete set of leather for a +8 DIY re-trim for about £2500 from Allon White. That was a few years ago mind.
I would hesitate to recommend the diy approach as Morgans are such individual cars and I would have concerns that a "standard" measurements kit would look as good as one that was "made to measure" and fitted by a skilled craftsman.
