Is it permissible to buy government land that has been seized, knowing that I cannot afford to buy land through official channels?

If government lands mean the national soil of the state, then this land is not called governmental. Rather, it belongs to whoever revived it or was first to it, and the state only supervises it. Ownership during the time of the Prophet, peace and blessings be upon him, and the Rightly Guided Caliphs, was through revival. Thus, "Whoever revives a dead land, provided it has no right belonging to a Muslim, then it is his," and "Whoever is first to a permissible thing has a greater right to it." Accordingly, if the land is owned by those who have taken possession of it by reviving it, or being first to it, or purchasing it from those who were first, then there is no doubt about the permissibility of purchasing it from them.