Cost for central heating

That sounds about right, unfortunately. We did this project seven years ago (had heat, but replaced entire system since we had asbestos ductwork and an aging furnace) and it was $9K then for a similarly sized house where we did not have to cut holes for the registers, so it would not surprise me at all if it were $13K today with the additional work. I would not try to part it out--you need permits for the furnace installation and it's better to do it all together using someone reputable, since the risks if it is done incorrectly are life and death (gas lines, carbon monoxide, etc.) That said, you can certainly ask them to cost out the furnace separately and you can tell them (as we did) that you want a less expensive option--we chose a slightly less efficient model that was $500 less than their recommended model. A good HVAC company should also be able to help you strategize on where to place the vents and how to size the furnace, which is really important. Certainly get a few more estimates, but I would not be too surprised if they're all in that range. Be sure to check out the state rebate programs to see if you are eligible to recover some of the costs that way, too.

That seems slightly high. We just put in central heat and AC for $10k in Oakland for a home with the same square footage.

It's hard to do a true apples to apples comparison without knowing the exact scope of work required for your project, but I can give you some figures based on a furnace replacement and duct upgrading project that I had done in 2016. My home is 1315 sq ft, and a split level. 

The total project cost (before rebates, see https://www.bayareaenergyupgrade.org/) was around $11K. This included a mid-tier furnace (Carrier Performance Series 96.5% 2-stage), Nest thermostat, asbestos abatement ($700+ alone!), duct replacement, and limited air infiltration reduction (air sealing) for the attic and crawlspace. We qualified for about $2K in rebates, which we received a few months after the project was finished, which was really nice. 

Your estimate does sound a little high based on my very limited experience, so I might try getting at least one other bid. We went with Hassler, and overall were happy with them (project came in on time and on budget), though there were a few bumps in the process around scheduling and comms. Basically, you need to make sure that someone is home throughout the job, every day of the job (and ideally the same person bc the team is not always the same, and you have to re-communicate A LOT). 

One suggestion is to ask your provider to leave the option to add AC in the future. This should not cost you extra (maybe a nominal fee), and will give you the physical space to add AC, should you choose to do so later on (it has something to do with leaving enough space for the coil, if I recall correctly).

That estimate sounds way too high. We installed heat in a 1600-square foot house without central heat about 10 years ago and paid $6K total. It's still working just wonderfully.....

We paid about $10k for a similar project last year for our 1350 sq ft home. However, the house already had central heat, they were just replacing the furnace and all the ducts under the house. Not sure if your project would require more labor to add the vents and ducts inside the house

We're in a similar situation, with an 1100 sf house and an old wall furnace in the hallway. We priced it out, and got an estimate for about $7k. I'd suggest getting a few more bids.

I suggest you call Bobby, owner of Apple Heating and Air Conditioning at 510-459-8868. He has installed new furnaces and ducting for our friends as well as us and done a terrific and reasonably priced job. He is honest, thorough and knows his business well. Have him take a look at your situation, make suggestions and give you a bid. It should be a lot less than the one you received. Feel free to tell him Roger sent you so he will know who recommended him.