I know some modern day treaties give compensation for disputed lands, but the Alaskan and Gadsden purchase weren't really "disputed", as far as I know (though a minor argument for Gadsden might apply). They were more of straight purchases of land. I know the HRE and British Empires did quite a bit of this, but are there modern day examples? as in post WWII. I tried to look up from the soviet breakdowns, but didn't see any, nor to the crashing of the French and British empires in Africa and Asia. I don't mean leasing ports or army bases, but straight "We want this land as part of our nation, and here's some money for it" treaties.
In 1890, the UK and Germany signed the Helgoland-Zanzibar Treaty. Helgoland is a small island in the south eastern psrt of the North Sea that prior to 1814 had been part of Denmark. In 1890, Great Britain ceded the island to Germany in return for Walvis Bay in the German colony of German Southwest Africa and for Germany to give up their attempts to take control over the island of Zanzibar, off the coast of German East Africa. While Bismarck himself negotiated this treaty, he misrepresented it in the German media and went as far as denouncing it as a "bad deal" and said "We traded trousers for a button". All of this was just to weaken his successor, Leo von Caprivi, who only lasted four years as Chancellor of Germany. In 1899, Germany bought the Marianas, Caroline and Marshall islands from the nearly bankrupt Spanish Empire.
Source: Bismarck's Imperialism 1862-1890 by Hans Ulrich Wehler