A couple of quick thoughts:
- Ceiling: - "Ceiling will be painted as seen in commercial spaces." What this implies to me is that you plan to paint the bare ceiling joists, underside of the upper subfloor, and any exposed ductwork or plumbing with black paint, as I sometimes see in a commercial space with an exposed ceiling. If you have other family members, you should consider whatever type of soundproofing you can afford so that you can listen to movies or music without disturbing others that may be in the upper level. Drywall with insulation would be a good start but there are other products you could consider, that some here with dedicated listening rooms have used.
- Speakers: Since you are budgeting, you might consider starting with the most musical, while also being dynamic, HT speakers you can afford and dual use that area for movies and music until you can budget for a separate music system. This review discusses some older products that are still sometimes available used. Fremer had only good things to say about them, not only for HT but also for how they handle music. That same company still manufacturers speakers and still offers a couple of HT options for purchase new, including a dedicated on-wall or in-wall front channel model, a large center channel, or its smaller sibling.
Good luck and have fun with your build.