Torquay made it five unbeaten games from the last six following a goalless draw with Accrington.
Midway through the first half Torquay winger Danny Stevens broke down the right and his cross was swept wide by Martin Gritton.
Gulls goalkeeper Scott Bevan was twice called into action in the 28th minute, first when he was forced to dive late to keep out a deflected drive and then, seconds later, to hold a 20-yard shot on the run by Sean McConville.
United countered with Ellis' free-kick from the halfway line helped on by Gritton and visiting keeper Ian Dunbavin saving Chris Zebroski's volley on the spin.
Home boss Buckle - League Two manager of the month for a four-win August - sent on three subs to try and gee-up the home attack but it was Bevan, again, that needed to tip over James Ryan's angled effort.
The home keeper then making a breath-taking stoppage-time reflex save to keep out Andrew Procter's powerful downward far post headetr.