I would be slightly wary of dealing with Shetland boats. If you look at
(which is a nothing to do with the manufacturer) on the forums a couple of people have had nothing but trouble with their dealings. There a couple of historic threads recommending other companies that will make frames and covers for half the price.
If you do have any dealings speak to James (Reiman) the owner but it does seem that there attitide towards customer satisfaction is less than desirable.
I don't know what is going on there but to give you an example their new website was due to be launced in October, then November, then moved to December. If you look at www.shetlandboats.co.uk
it now says that they are relaunching it on 21/2/08 and the same notice is there today. It doesn't strike me as a particularly great business.
Good luck in your search
Please note that this is not based on personal experience but it does seem that the latest incarnation of Shetland is a far cry from my father bought his boat from them years ago.