You can obviously spend anything on building a golf course, I dont think you get what you pay for by paying much more than $5,000,000 for the lot, most figures upwards of 5M are just wasting money and largely thats backed up in the resale's price.
In the UK, Greens cost $20,000 perhaps 30,000 so multiply that by 20, tees dont really cost much, perhaps $5,000 per hole, Irrigation perhaps $400,000, for greens, tees and twin row fairway. Shaping costs perhaps $200,000, Drainage another 150K, Seeding is about 50K.
A reasonable clubhouse might cost $750,000, $250k for the furnish, $400k for machinery, car park, roads, maint store, project management a $100,000 design fee and the land cost. Things can be much skinnier and its my experience the skinnier the better if you are thinking of making a profit. Location is everything in the UK, a golf course in the herbrides might look great to a few but not to a banker, it needs people and lots of them.
I have got very busy again because my customers want things done at a reasonable price, I can probably build 18 holes for less than most architects design fees. I just cant see the Western world wasting money again and making the sort of mistakes that got made.