This article from the BBC
is interesting, as this is something we have experienced. The timber products have had 2 prices rises this year from the supplier due to the increase in global demand for timber. This has unfortunately made the timber sheds and other garden products a lot more expensive.
Another recent development is the pond manufacturer has been having problems getting hold of the specific required plastic to make the preformed ponds, so currently the Large has gone out of stock, with only the medium and small preformed ponds available, and these will probably become unavailable at some point when stock is depleted. If you were hoping to get a large pond, the main option is the plastic pond liner, or alternatively you could opt for 2 medium ponds, which is 400 litres, and combined just 20 litres less than the large pond, and just £5 extra, with no delivery sucharges to pay. These can be placed long ways to create a longer, narrow pond, or can be placed near each other as a double pool pond, with some pond edging plants, placed between them.