The home side put in a very disappointing performance, particularly following their display against Maud the week before, with the Banchory midfield allowed to dominate the proceedings, laying the foundations for the visitors' win.
United passed
up an early opportunity when Cammy Bruce cut the ball back to Matty Edmond whose effort with his favoured left foot went harmlessly over when it looked much simpler to take it with his right.
United conceded a silly free kick just outside their box, but Stainer's shot ran straight through to Richard Bowman in the Ellon goal.
The visitors took the lead in the 10th minute. The United midfield were posted missing when Banchory broke quickly on their left with Watt's ball into the middle finding Stainer, with time and space to pick his spot.
Ellon looked far too pedestrian in their approach, but came close when Chris Allsop beat keeper Sim to a corner only for his header to fly over. It took a fine double save from Bowman just before the break to keep Banchory's advantage to a single goal at half time.
United looked more determined at the start of the second half. The introduction of Keith Reid added some bite upfront and the home side almost equalised when the Banchory defence struggled to deal with a cross from Neill Irvine. The ball broke out to Keith Reid but his shot was cleared off the line with keeper Sim stranded.
Banchory extended their lead in the 70th minute when the home defence were unable to clear their lines, and McRae took advantage to grab the visitors' second.
A long range effort from Graham rattled the Ellon woodwork, and the home side responded with a fine curling shot from Cammy Bruce, which appeared to be dipping over Sim, but the keeper's reactions saw him tip the ball over for a corner.
Any remote chance of a late fight back from Ellon disappeared in the rain and gloom when a long range free kick from Courage was somehow missed by everyone and landed in the back of the United net just to typify their dismal afternoon.
ELLON UNITED: Bowman, Annand, McCraw, Henry, Forsyth, Irvine, Paterson, Bruce, Huggins, Edmond. Subs: Reid, Petrie, Cadger, Chalmers, Morrison, Clark.
BANCHORY ST TERNAN: Sim, Watson, Shand, Galashan, Moir, McRae, Ogston, Graham, Stainer, Horne, Watt. Subs: Henderson, Courage, Smith, Carrol, Smith, Garret, McLelland.
Ellon United must pick themselves up for this Saturday when they face another tricky home fixture against Dyce at The Meadows, kick off 1.45pm.