How much would materials cost for insulating a 1.5 garage?
If you are just planning on going to the local home improvement store you are probably looking at roughly a dollar per square foot for materials. That would apply for both the walls and the ceiling. I would highly suggest you look into Air Sealing and purchase a few cans of foam to do this with. People out there don't understand air sealing and it is just as important as insulation. It's a missed opportunity if you don't address it before/during insulation.
The local building suppliers will sketch out the budget for free, if you ask the right people. In my area that would be at least $8,000, with R38 in the roof and R19 in the walls, if you're planning to heat it (environmental code compliance). This is based upon being 2/3 of what I had built about 14 years ago in a northern climate, with post-and-beam bents and standing-seam roof 12/12. The high today was -3F, for reference, and hasn't been above 32 for over 10 days.
rephrase your question please 1.5 what? to what degree of insulation?
what is it -- 30 feet long by 15 wide? [9 meters by 4.5 meters] how much insulation did you think to install -- in R factors? you'll have 450 sq ft of ceiling and, with eight foot walls, about 670 sq feet of walls [excluding the door for autos] suppose you put kraft faced R-13 in the walls and kraft faced R-19 in the ceiling [that's 3.6 inches and 6 inches nominal thickness] -- you can then look up the materials cost at your local home improvement store. add 5% for nails and tools. That's the DIY cost. If you have to hire labor ... get three bids from contractors and LISTEN to their advice on how/whether to do the job. In my area, that's about $750 DIY total including sales tax. In my area, such insulation "usually" goes on sale in February. You might get 20pc discount on sale.
A bunch because after the insulation comes the finishing of the interior of the garage. My guess is $5,000 because you will want to add some electrical circuits. If you want to add plumbing, then another $5,000. That is material and you do the work.
Even after your Update and Update2, there isn't enough information to accurately estimate the materials required, much less the cost. Short of actual blueprints, nothing you post will answer that question.