A kilt must not have tartans.
Kilts can also be solid coloured.
And the fabric needs not be wool or PV. Tweed kilts are gaining popularity. Or how about a kilt in a nice camouflage pattern, or denim, or leather?.
They can be in traditional kilt style, or their design can deviate to the extent where they become utility kilts - or skirts.
Many kilt makers or vendors have these kilts in their assortment. Here, I shall simply link to already mentioned vendors if they are also offering these kilts.
Solid kilts are mostly about the same price as equivalent tartan kilts. Tweed kilts shall be more expensive than wool kilts. 'Imported' denim kilts shall often cost more than tartan kilts from the same vendor, whereas 'locally' manufactured denim kilts may be cheaper as their tartan cousins.
Camouflage kilts shall be cheaper, whereas leather kilts, what is to expect, are way more expensive than equivalent kilts made of in wool or PV.

In a black kilt and flat loafers, Düsseldorf.
Solid coloured kilts
No doubt, what most people connect with a kilt are the tartans. Probably they more than anything else signalize kilt. But, like just said, tartans are not a must.
Typically, solid kilts are black, but they may also be grey, green, blue, brown, and red.
Cheap
Kilt & More
Schottenrock. Germany /
Kilthomme, France /
Kilt & More, USA
Kilts in solid black, green, and grey.
Moderate priced
Clan by Scotweb
You can have solid kilts in no less than 31 different colours or shades, in 5-yard, as well as in 8-yard, and in pure new wool!
Prices look attractive, making these kilts definitely something to go for if you are in the market for a fine solid kilt.
More expensive
Paul Henry
Tweed kilts
Making kilts in tweed is a rather new thing. One of the first to offer kilts in this fabric might have been
Paul Henry
A 5-yard tweed traditionally styled kilt starts at £425, which is almost £100 more than a 5-yard wool kilt, as of mid-February 2022.
Clan by Scotweb
is somewhat cheaper, their casual tweed kilts starting around £230. They are to have in 274 different fabrics, some more expensive than others. You can also have them in eight yards, at a higher price, of course.
Denim kilts
Where you should otherwise wear denim jeans or shorts, a denim
kilt could be the solution.
You can have them very casual, most often in utility kilt style, like from
Kilt & More
They come in different utility kilt styles, most of them with too many pockets, I think. Without pockets they tend to be more expensive than with them.
I might be tempted to pay just a little bit more with
Clan by Scotweb
and get their 5-yard traditionally styled denim kilt, selling at £125. At a premium price you can also have it in 8 yards.
Paul Henry
Paul Henry is known for making very nice denim kilts. They are around £200 for a 5-yarder.
Leather kilts
You can get them 'relatively' cheap from
Kilt & More
in either utility kilt or some gothic style
and from
Clan by Scotweb
at around £500. Then the kilt is traditionally styled.
Contemporary kilts
1stCentury Kilts
Expensive top-quality kilts where innovation is based upon tradition. According to
Howie R. Nicholsby, founder and owner of 21st Century Kilts, the kilt should be an alternative to trousers and for every man to use, casual or formal:
“My aim is to give men throughout the world a realistic alternative to trousers. Pioneering the next step of its evolution, 21st Century Kilts is true to the original kilt which was everyday clothing. Casual or formal a kilt should be an option for any man from anywhere who can realize they are part of the history of an international garment."
Accessories
How to accessorize kilt variants? There might be many opinions. My recommendations are: