The retailer you are talking about carries a much more substantial stock than most, partly because it is also a wholesale business. They will have their own business reasons for setting the level of the minimum order which none of us are privy to, though this explanation is offered on the web site.
"In 1994 our accountants made us aware of just how much, on average, it costs us to process an order.
We decided there and then that we had to have a minimum order value so we could cover our costs on as many orders, but not all, as is possible. Even with these minimums we still send out 100+ orders a week we do not make or lose money on.
Our minimums vary according to how long various types of goods take to be packed. Minimums on decals are lowest because decals and etched parts are the quickest and easiest to pack. Minimums on overseas kit orders are higher because these take longer time to pack. We will be looking at these minimums all the time and hope to bring them down as this website reduces the time, and therefore cost, it takes to handle an order."
I understand that it can be a little inconvenient, gone are the days when most of us could visit a local model shop to pick up a single tinlet of paint or bottle of glue. On the other hand I can't remember the last time I placed an order anywhere for less than a tenner.
At the end of the day you have a choice either to source whatever it is you want elsewhere (if that is possible) or make up the minimum order value with something else that you just know you are going to need sooner or later
Hannants has been going a long time so they must be doing something right!
And no, I don't work for or have any connection to the store, I don't even shop there very often
Cheers
Steve