My approach is the following:
I bought shares of a young joint forest. Young, because the forest has relatively small existing trees. These trees will continue to grow for the next 50 years or so. For the next 50 years, they will be a major carbon sink.
I understand that occasionally the forest is partially or fully harvested. When partially harvested, the pulpwood is used to make pulp and paper, which are relatively short-lived products, returning the carbon to the atmosphere. However, a partial harvesting only releases some of the carbon sequestered back. On the other hand, it makes the biggest trees more room to grow to the full length.
In the full harvest at the end of the lifecycle of the forest, a large portion of the wood is sawlogs, which are used to make sawmill products: lumber that can be used to construct wooden houses. In contrast to a house constructed from concrete (CO2 is released to the atmosphere), a house constructed from lumber is actually a carbon sink.
Now, if you want to permanently sequester the carbon dioxide, to calculate how much of the wood actually ends in lumber, you need to take into account that one cubic meter of lumber (that sequesters about one tonne of carbon dioxide from the atmosphere) requires about 2.3 cubic meters of sawlogs. Only about half of the wood in an old forest are sawlogs (the rest is pulpwood), so one cubic meter of lumber requires 4.6 cubic meters of raw wood.
So, to sequester 250 tons of CO2, you need 250 cubic meters of lumber, which requires 1150 cubic meters of raw wood. 100 cubic meters of growth per year will remove the emissions in 11.5 years. Then, after that, you own a carbon sink worth of 21.7 tonnes per year.
How much hectares is needed for 100 m3 / year growth, then? In the southern Finland, one hectare grows at about 7 m3 / year. This means 14.3 hectares is needed. One hectare costs about 6000 euros (depends on the age of the forest; for carbon sequestration purposes you might want to prefer young forests that are fortunately cheaper), so about 86 000 euros will buy you the sink.
Now the fun part. Where I live, car drivers pay 500 EUR / tonne of carbon dioxide emitted in the form of quite many various taxes (at the same time carbon emission rights at the European emission trading scheme trade at 20 - 30 EUR / tonne). That has not caused car drivers to switch to electric cars in a major manner. If you believe one tonne of carbon dioxide emitted is worth 500 EUR, then your sink of 21.7 tonnes per year is worth 10 850 euros per year. That's a whopping return rate of 12.6%! Ok, that return rate is very speculative, because currently forest owners are not compensated for the carbon sink they create, and if they will be in the future, it's far from certain the rate is 500 EUR / tonne.
However, do note that forest growth rate varies depending on the location of the forest. So, I don't intend the figures in this answer to be absolute universally valid truth. You need to analyze the local forest growth rates if you buy the forest in your local country.
Somebody might protest that if you buy forest, some other person is selling it at the same time, creating no new forest. This is false. By buying forest, you are affecting the price of forest: the increased demand causes a very minor increase of price. Because forest increases in price as you buy it (although in a very minor manner), it becomes more profitable for someone to buy land that doesn't have forest in it, and plant a new forest. Much of the forests of this planet have been destroyed because people aren't interested in owning forest. If everyone was interested in owning forest, the destruction of forest would cease, and much new forest would be planted.