at least 450,000 EUR must be spent on a property if it is on the coast in the south of the country;
at least 250,000 EUR must be spent on a property if it is in the north of the country where the government is actively developing ski resorts.
Additionally, 100,000 EUR must be invested in the national fund of economic development. At least 22,000 EUR (subject to the number of your dependents) must be paid in extra fees necessary for processing your application. In 5 years, you will be able to sell your real estate in Montenegro and get part of your money back.
Please bear in mind that, if you plan to get a second passport, you can invest only in the properties that have been approved by the authorities of Montenegro. Usually, the list of such properties is not very extensive. If you prefer to buy outside of this list, you will only be able to get a temporary residence permit. As a resident of Montenegro you will have to wait 10 years before you can become a citizen instead of 6 months.