Ds1 (8) has a verbal dx of Aspergers and is awaiting formal assessment.
He is just the same. He hates wearing trousers that don't have a soft waistband, not such a problem when he was little as they do those jeans that have a jersey waistband attached, but not so easy now he's bigger. He clung onto a particular pair of Winnie the Pooh fleece trousers for years iirc they were age 3 and he was still insisting on squeezing into them when he was 6! Fortunately he is small for his age and has a tiny waist and no bottom, but he still looked most odd with his trouser legs constantly at half mast. He kept them for a year after they would no longer fit and has now grudgingly agreed they can go to his brother - but under no circumstances must they leave the house. (The thing is, his brother is now 6 and not at all small for his age, so they just reside on a shelf in the wardrobe.)
He is the same about toys. Ds2 has a big sort out and give away to 'children who aren't as lucky' before every birthday and christmas. He will give away almost anything and is generous to a fault. Ds1 however usually manages to be persuaded to part with something like one small toy out of a kinder egg and he find that so difficult. He has a whole cupboard full of little bits of mostly unidentifiable plastic things from kinder eggs, party bags and comics etc. He never even looks at them, but there is no way he can be persuaded to part with even one tiny thing out of that cupboard.
I also remove things every now and again when he is at school. I tend to bag them up and store them in the loft. Then, if he hasn't noticed they've gone after a year, I get rid of them then. If he notices he is told they are in the loft and as I have had to on occasion fetch things back down that he's missed and got very upset about, he now thinks everything he's ever owned is up there. (Which would be clever as our loft is tiny and still contains all my late father's belongings!)
He is the same with haircuts as well. He will only agree to having a haircut if he can no longer see out and then only the tiniest smidgeon is allowed to be cut off. Fortunately he has lovely long surfy type curls, and this is a fairly popular look at his school, otherwise I could see this being a problem. He also refuses point blank to go to a barbers (can't stand the sound of the clippers or not being able to control which channel they have the tv on ) and will only go to our local ladies hairdressers who charge a fortune.
On a bigger scale, but I feel in a similar vein, he simply cannot cope with the idea of us ever moving house. Huge meltdowns, followed by days of being unsettled ensue if anybody even moots it. Not good really as we are a family of five and three dogs living in a tiny old house that needs a lot of work and there are complicated family related reasons why we really would prefer not to stay here. I can't see us ever moving though to be honest, as I think he sees the house as his security blanket and we couldn't take that away from him.