There is a local crushed rock available. Not sure it will work or what its characteristics are though the size is about the same as course perlite. I would think a pumice/lava rock would be more absorbant than perlite. Thought perlite was strictly used for areation. Assuming that was the case, then I would think any crushed rock would do. Obviously I'm wrong about that. If I could easily find a 4cf bag of perlite that was affordable, I'd buy it. The stuff I found is not course enough though the price was right. Small bags of perlite cost too much. As for the peat, I can buy a yard of crushed pine bark locally and get 1/2 yard of fine bark and dust from screening through an 1/8" screen that could be used in place of the peat, and a lot less expensive than peat. I'm just trying to put together a good mix that will work with what is easily available at a price I can afford.

I disagree totally with Dave :-) Mulch and compost can be used interchangeably - mulch is simply a soil topdressing and can be comprised of any number of materials including both organic and inorganic products. There is absolutely NO reason why compost can't be used extremely successfuly as a mulch......it's the only type of mulch I've used in my garden (and many clients' gardens) for years. If applied in an appropriate thickness, it has the same weed supressing capacity as any other mulch, it insulates the soil to the same degree and retards evaporation of soil moisture and IMO, looks as good, if not better, than other commonly used mulches like bark nuggets, pine straw or wood chips. And it has a greater ability to provide nutrients and improve soil structure than most other mulches. With regard to weed supression - a 2-3" thickness of any type of mulch will prevent most existing seeds from germinating. Seeds that blow in or travel from existing plants elsewhere can germinate easily in fine textured compost, but that is also the situation with most other fine textured organic mulches, like ground or shredded bark. The coarser the texture or larger the size of mulch particles, the less readily blown-in seeds will germinate. I will agree that the quality of any commercial compost can vary widely. Fortunately, I live in an area that pioneered municiple composting from yard waste and that compost is tested regularly for a variety of possible contaminates, is certified organic, has a good chunky texture and rich, dark, earthy color and aroma and is distributed and sold throughout my area. Many professional horticulturists and landscapers swear by it. YMMV.

If I may, I would urge you to reconsider Norway maple. A bad invasive thug in N. America, I'm afraid. One or two of your other ideas may be less winter-hardy than your locale requires, but no harm in trying. But Norway maple escapes from cultivation via seeds, and into the woods it goes, crowding out native tree types. That's not hypothesis....this is really happening in places like New England, Wisconsin, Michigan, etc. No reason why the same would not happen down by you.

I previously had black beach stones as mulch , they looked good for many years, the color did not really fade ( even though I live where the sun shines almost everyday ), i think the color softened some. I had a weed barrier cloth placed under it, available everywhere, or use sunshade cloth. The only thing I noticed is that it showed some water deposits, from frequent watering, but very hard water where I live. i now have very small beach pebbles as mulch , changed my landscaping to a very MCM look ( very Palm Springs looking ).