About 450 members and supporters of Prince George's County government unions paraded through Upper Marlboro last night in an orderly, almost cheerful demonstrations against the employe wage proposals of County Executive Lawrence J. Hogan.

The march preceded the County Council's final Public hearing on Hogan's proposed budget for 1980. And although union leaders described the gathering as "an historic moment for county unions," the crowd that heard them was substantially smaller - and quieter - than the more than 1,500 union supporters who appeared at the council's first budget hearing two week ago.

Ten county unions were represented in the march down the normally sleppy streets of the county seat, and 96 speakers signed up to address the council. The resulting arguments and issues varied little from previous hearings.

Union leaders once again criticized Hogan's proposed 3 percent cost-of-living increase for county employes as inadequate, and his estimates of county funds available for next year as deliberately understated.

Once the public hearing began, supporters of the unions school health aides, elementary school guidance counselors, and programs for the handicapped, among others-again asked the council for increased funding for programs that Hogan has cut back in the first year of the county's tax-limiting TRIM charter amendment.