My daughter has really enjoyed Mark Kistler's online art lessons. She completed all the sample lessons (it took her and her brother at least 2 months) and still wanted more so I purchased a membership.
The other resource I purchased for her was Klutz's Watercolor: For the Artistically Undiscovered.
In addition we have several art reference books: The Usborne Book of Famous Paintings, 13 Paintings Children Should Know, Usborne Art Treasury (exploration of different media and styles) and Children's Book of Art.
Lastly, I can sympathize with your art instruction difficulties. I live in a very artistic town and it still took me a year to find an art instructor for my daughter. It was frustrating because In my city most of the children's art classes involve craft projects during after-school programs, the upper level adult watercolor class refused to let a child attend and many private instructors had surreal, faintly disturbing art styles my daughter didn't like. It's been a difficult process and I'm still not sure I've found exactly the instruction my daughter needs. Next step is to ask the community college if they will allow a 10-year old to attend their drawing classes.