You do have to remember though, that when selling at market you are selling live weight, and when dealing with customers direct, you are looking at the weight of a finished, trimmed butchered carcass.
At this time of year a 38 kg lamb may only produce a 17-18 kg carcass and a proportion of that will be low value meat. You also have to factor in the cost of killing and butchering - it all adds up. We have sold direct in the past, although we are not in a good location for this. By the time you add up allthe extra costs associated with selling direct to the customer, we reckoned we were only getting about and extra £5 per lamb. If you added all the extra labour in to it, there was nothing in it at all. In fact we were slightly better off by not selling direct.
Most of out lambs (the ones not kept for sale as breeding stock) are now sold direct to the abbatoir. Their fieldsman comes out and picks through them and then they send a trailer to collect them. Price is OK - and no hassle or outlay on our part.
I'm not saying that you can't add value to lambs by selling direct, only that it is not a silver bullet and you need to weigh up the costs carefully.
I agree though with your premise that we don't get paid enough for our lambs.