Problem I'm struggling with at the moment.
There are, if you google a bit, a pletora of rather cheap Pakistani knot makers and retailers.
Even WKC sells these. They are in general not badly made, but always a bit off the regulation patterns it seems. Empire Costume says they make them in house. Quality looks much better, but the prices are on the up too. Then there a some US retailers, like the Quartermaster General and others, like the Hussar Sadlery who have ACW knots, but again also sell the McD knots from Pakistan.
You have Uniformstore in England. A retailer of Pakistani made knots also. In Belgium there is Mc Farthingdale or gale. They also sell those Pakistani knots.
It looks like the Pakistani's have cornered the market for the cheaper knot.
That is why I tend to make them myself, which isn't very difficult to do. For Officers knots I found that in order to copy an original sometimes I have to buy two different cheap knots to be able to make a good knot and as close as it gets. That still often would be cheaper than to buy one from EC. The pakistani knots tend to look very garish, but a bit of brown shoe cream makes them ,,antique'' in no time.
Just for the fun I now play with the idea to order all needed stuff like gold braid, tassel strips and assorted other gold laces and bits from the store and so how that goes.
Knots in general are not very difficult to make, be it leather ones for troopers or the gild knots for officers. And the quality would be way better than the McD knots.
Turksheads I learned to make with the help of youtube. Sometimes these function as sliders and often also as decorative element on the knot body. Zig zag scissors you'll need also and for troopers knots a load of old belts to cut down for lanyards. If I say so myself, I made some pretty convincing Blucher and other specialty trooper knots which would have cost me a lot if ever found in the wild.
And you probably never will.
Those special knots are not made by our Pakastani friends. No market.
I find it very satisfying to make this stuff myself.