Dedicated Kimono Websites
One of the most trusted sources for kimono. Ichiroya sells kimono, obi, shoes, and many other items. Their descriptions are very accurate and they will always pour over the kimono and report any flaws. The website has a nice advanced search option for finding exactly what you need. And they are also very helpful if you need individual help. Their prices are on the more expensive side, but they're a great source for high quality kimono.
I have personally worked with this store when they came to Boston. The owner is knowledgeable and fair, and I give this store my personal stamp of approval. They're LGBTQ+ friendly and willing to help you with whatever your dressing needs may be. You can find various kinds of kimono, obi, dressing accessories, tabi, haori, purses, kimono fabric, etc. The website lists product condition and sizes. They operate out of Ohio (no surprise) and for now only ship to the US. But their website also has various information, a blog, youtube channel, instagram, customer gallery, and more! I strongly recommend you check them out! I wrote a whole blog post about them here.
Kimono Yukata Market
This site sells yukata and other accessories necessary for wearing yukata. You can buy an obi and geta set with any yukata. They even have special kimono underwear, nagajuban. They also have a small selection of Japanese art and display stands.
A store that sells various items, such as kimono, yukata, jinbei, hanten, aprons, and fabric.
An etsy store that includes very beautiful handmade items and other more traditional products. Great place to find modern fashion items made from kimono, dressing accessories, fabrics, and more. They accept customer orders and happily accept other individual requests.