Much depends on the type of lamb and the weight (which can vary from about 7 to 10 kilos) ~ Organic will cost up to 100% more. Lamb from the "High Fells" is also a premium priced product as is that from the Welsh Salt Marshes. Certainly it can be found cheaper if you can collect from the farm shop and cheaper still if you can find a small abbatoir that will sell to you. That applies to most things. We are currently paying 75pence a pack for Welsh butter, buying it direct from a local creamery. In farm shops around here the same product is on sale at anything from £1 to £1.35 a pack. Supermarket prices are from £1.35 to £1.58.