Hi, Steve!
I have personally seen a handful of our customers that sell specialty paints in their Weebly stores. Specifically, paint for refinishing furniture to a shabby chic look. Cabinet maker's stain and mixes, along with exterior paint for historic homes. Each of these examples has its own niche market, but some paints and stains are a bit difficult to get in some places. The big box home improvement stores may not carry the exact product you are looking for or you may want something that is different from what everyone else is using.
We also have a lot of woodcraft and DIY crafting websites that carry small batches of paints, stains and gels. That would cater to the individual who builds for themselves or sells their own products on a small scale.
However, I certainly think that ordering paint online isn't any different than buying wallpaper or clothing. There is no way to know exactly how the product looks or feels without seeing it in person, as you have said. But that certainly has not stopped buyers from doing it.
The goal would be to get the product into the potential buyers hands without them spending a lot of money up front. Only to find out they have chosen the wrong color/blend/finish etc. And for that, a couple of ideas come to mind.
How to help the customer pick and choose what they need?
1.) Color guides. Create 'true to color' guides that could be mailed out for a nominal fee. For stains and finishes use thin crafting wood in popular species such as (pine, oak, ash, hickory, basswood, etc). I suggest thin crafting wood simply to make it lighter, which would keep shipping to a minimum.
For paint, you could do the same thing or even use color chips, pamphlets, etc.
2.) Individual samples. Just like those, you would see at the large home improvement stores. With just these samples, it would eliminate the buyers worry on spending a bundle on the wrong color. This option would also give them the opportunity to get that product in their hands. Have them try it to see the quality for themselves and if needed order more samples until they get the right color.
Think outside the box. Go after a new group of loyal customers that would re-order regularly. Including those remodelers and crafters, you spoke of. But also, furniture, cabinetry and interior designers. Who spend a lot on finishes. Many of which do not have time to waste driving from store-to-store looking for the perfect paint, stains or finishes. Ordering online is certainly becoming the way to go and that even include paint.
This could even open up opportunities for selling wholesale to small businesses who want to carry your products. If that is something you are interested in doing.
P.S. My husband, who previously owned a custom cabinetry company, has even purchased stains online. They were in one and five-gallon sizes. He simply couldn't find exactly what he needed locally. That was a least 15 years ago. Selling paint and stains online definitely isn't new. You should be just fine. 
I hope this helps, Steve. Let me know if you have any questions.
