As someone with a baking business I attend a lot of these events and that sounds pretty standard.
As others have said, there’s a lot of overheads for small businesses. Bear in mind the stall probably cost £25-50 depending on where it is. So before they even start turning a profit they need to sell up to £50 worth of stuff. There will be fees to take out of each sale for using a card machine, the cost of a box, so maybe £1-1.50 on each set of 4 has gone.
Have you seen the price of chocolate these days? I buy bags of Belgian chocolate chips that were £25 last year and are £40+ this year.
If they’re putting Buenos, Creme eggs or Reeces etc in the cookies, that’s easily another £1 or 2 gone on fillings, plus butter at £2 a pack, brown sugar, costs a bloody fortune, good vanilla extract is £6-7 a pot for 60g which will be £1 a batch of 8 or 12 cookies.
Add that up and include even minimum wage for the baker (plus the time for their assistant to stand on the stall with them if they have one) and your cookies all of a sudden look cheap!!
If you’re comparing them to a pack of 4 from Tesco for £1.50 obviously they look like a lot, but it’s a completely different product and experience.
All that being said, nobody is forcing you to buy them, but if you want to support artisan bakers and entrepreneurs then maybe consider the value you get rather than the price.