If kilts are to be seen as trouser substitutes then there should be a range of prices available and kilts makers would sell more in the end. You would not wear a £200 pair of trousers to dig the garden. You would have several kilts for various uses and a good quality made to measure for best, same as you do for suits and trousers. I want to see the day when you have complete choice of kilt or trousers in all price bands then we might see more men wearing them on a daily basis.
I have to point out that kilts are currently available in a wide range of price points. You can get a cheap Asian import for next to nothing (you mention the Lidl kilts). Here in the US we have Sportkilt. Between those type vendors and Ebay you can find something for less than $50, if that is the price/quality you are looking for.

Then if you want to spend a bit more there are some mass-produced kilts (again, Asian made) that are of better quality. Stillwater kilts have some in the $100 to $150 price range.

Moving up from there you have some vendors having MoD style kilts reproduced in Asia for between $200 and $300.

Looking at USA Kilts, they have casual kilts in Poly viscose starting at $99. They have a style called "semi-traditional" starting around $220.

They also make wool kilts, as well. Many vendors offer wool tartan kilts. And almost all of them offer some form of casual or lower yardage option. These may be in the $200 to $300 range.

Then, of course you have you typical 8 yard kilt, which is often available in a variety of weight wools, which will run you anywhere from $400 to $800 depending upon the vendor, quality, and other factors.

Of course, the higher you go in the price scale, you can expect better quality. But all this is to say that you can, right now today, find kilts in a very wide range of price points.