The Price is Right?

Kit - some make their own but many rely on others to make costume for them; either off the shelf or custom designed. But costume varies so greatly in cost - why is that? A bit of research was a real eye opener.
 
Much "off the shelf" kit is mass produced overseas. A design or item is sent and they copy it with astonishing efficiency in countries where overheads in terms of taxes, materials and labour are vastly less than the UK. So, sale prices are low, but individuals all get the same design.
 
What if you want something more bespoke? Then you would likely use word-of-mouth and recommendation to choose a UK based producer of costume. Some of these individuals or companies also produce items in bulk to sell at fests, so you get a more unique item but at less than the cost to design a piece for you.
 
Say you really do want something made just for you that you cannot buy ready made though...then the UK based artists we spoke of would consult with you, get measurements, choose materials and colours, maybe even fit the finished article to you. How do they price these items?
 
According to my research a good rule for pricing something made by hand is to divide the cost of materials by 0.35, this in no way ever covers the precise amount of labour or time though...but using this method lets have an example-
 
Glenda the Barbarian (who has mighty thews) wants trews, in real wool, with a comfy liner!
Her artist Sandra the Seamstress has to source 4 yards of good wool, a spool of thread, 4 yards of cotton- and ignoring buttons or time the cost of these is £55 divided by .35 = £157
 
I BET you have rarely had to pay this much for Sandra the Seamstressesesss(I don't know when to stop that word) trews though! So as a hobby are our creative folks under-selling their time? Is this what the pressure of cheap imports is doing to them? I for one worry that eventually they will find more lucrative pay per the hour (maybe a paper round) leaving imports, or making your own as the only options.
 
If you are a kit maker in the UK, how is your business faring?