Yes, Graham, land and property is cheap over here and I think building materials are too, anything that is imported though can be more expensive, say, maybe some of the technology.
I don't think you'll have any problem finding building materials, my husband used to say that wood was expensive over here, and not ‘dried', cured, I can't remember the right word for it. There are also several big DIY shops in Varna similar to B&Q that sell everything from screws to furniture.
There isn't any tax over here when buying, we had to set up a business in order to buy though but that has been dropped now, although it might come back in after ‘brexit', how fed up I am of hearing that word!
I have to pay an accountant to do ‘nil' accounts and put them online every year. The tax will come when you sell your house if it's on a business any difference between what you pay for it and what you get for it will be viewed as profit.
Hope that helps
All the best
Sue