Construction Costs

Jesus H Christ this is too vague for even the most preliminary estimate lol. Off the bat, what is the structure being demolished? How many stories? Is it concrete or steel construction or wood framed? Is the earth contaminated? Does it need soil improvements for remediation before building on it? For your new 'commercial' building. Is it retail? Office? Does it have multiple floors or all on one level? These are probably the major items needed to assume any kind of unit price. I know you are looking at super early budget unit pricing but even these basic questions give you a few line items to get a better idea of cost at this stage. Also, it helps if you can bluebeam up a sketch of a proposed site plan (you don't need an architect for this). This will help you get way better feedback on unit costing.

As pere said, not anywhere close to enough information in your post.

So what is the proforma for, is it a case study for an interview? It seems kind of complicated given those parameters, or I could be wrong?

With such vague terms, and this early on in the process, a good proxy is $5.00 per GSF. Very rough estimate, but this is a good place to start.

This seems remarkably specific. If you're a developer or work for a developer, you should know or someone in your firm should be able to put together a rough back-of-the-envelope estimate for something like this. If you're an investor, you should be able to contact someone with construction estimating skills for this. Looking for the answer on an internet forum seems like a bad process if you're making a real investment decision.

If this is in fact part of a case study for an interview, use the $5.00 psf estimate above and just say that you don't know what the real cost is, but you used that number as a plug and would verify it as part of any normal due diligence process.