If you think £5/10 is too dear for a quality file,you may be at the wrong game. Good tools do not come cheap,at the beginning,but end up being the cheapest in the long run. How do I know ? been there ,done that,have a box full of junk to prove it !
I,m still using tools I bought 50 years ago,they seemed dear at the time,but now ?.Along the way I was tempted by "bargain" offers [like many of us ],then I got sense and left them alone. A good file is a pleasure to use,while a bad one is a pain-in-the-arse,and sometimes in the hand as well.
You dont need a full set,just two or three to meet most of your needs and add to to them as required.Suppose you spend £50 on your files,how many pints will you buy for that,and how long will they last you ?
£50 over how many years ? No contest ! Go for it and enjoy using proper tools.