D.B.
Target just rolled out a whole line of adaptive clothing for kids. Designer Tommy Hilfiger just did a big project on this too - I saw a report on TV. While his stuff might be more expensive, it might be worth it. If it's too much, you might get some ideas there and then see if you can find some alternative at lower cost.
They've gotten away from buttons and zippers and more into snaps and even magnets so things line up easily. There are also a lot of things without tags if she has any sensory issues.
Can she manage elastic waist pants herself? Sometimes just pulling up is much easier than doing a fly and a button. Otherwise the magnet-front shirts might be easier than a standard tee shirt or sweat shirt. Also, some kids can't figure out how to put their arms in the sleeves of an open-front shirt/jacket/coat, but they can learn the "jacket flip" where they lay the garment down and put their arms in the sleeves, then flip it over their heads. That's pretty standard in preschools and elementary schools, for neurotypical kids as well as those with coordination issues or other special needs.