The striker slammed home a rebound from close range asÂ Main ran out 2-1 victorsÂ at Oxford Street and completed a league double over their neighbours.
Armthorpe, who have now lost nine successive games and sit just four points above the Division One drop zone, felt Gareth Roberts was wrongly sent off for a challenge on Buckham.
Alec Denton gave Rossington a sixth minute lead with a neat finish.
Roberts saw red just after the hour mark but Liam Radford levelled forÂ ten man Armthorpe from the penalty spot after Josh O'Neil was dragged down in the box, before Buckham settled matters late on.
Rossington boss Ryan Hindley said: 'You've got to beat teams that are in and around you, so I'm happy with that.
'I feel for Mike (Carmody) becauseÂ it's not a red card. The referee's got two big decisionsÂ wrong. It's not a penalty and I don't believe it's a red card.
'WeÂ dug in and had that bit of class when we needed it. We've takenÂ six points offÂ our local rivals but I'm not happy with the performance.Â I'm happy with the three points.'
Armthorpe boss Mike Carmody said; 'My players outplayed andÂ outbattledÂ Rossington. Anybody that tells you any different doesn't understand the game of football.Â I can't ask for any more from those players on that showing.
'What I'm upset about is the standard of officiating, which left a really bad taste in my mouth. It was never a red card. Both management teamsÂ and both sets of playersÂ will tell you it's not a red card.
'I felt we were the betterÂ team throughout the 90 minutes, playing some great football and creating good scoring opportunities which we didn't take.Â
'We limited Rossington to probably three opportunities and they took two of them.'
Harworth Colliery boosted their survival hopes, and moved to within four points of Armthorpe, byÂ comingÂ from a goal down to win 2-1 againstÂ Selby Town.
Ainsley Finney held his nerve to score a stoppage time penalty afterÂ Sean Ebbs had cancelled out Joe Dale's overhead kick.Â
The victory was Harworth'sÂ first league win in seven games.