Easter, who saw a deadline-day move to Championship side Plymouth fall by the wayside, was once again missing from the squad after being left out for the 1-0 win over Bradford on Saturday.
But the absence of the want-away striker allowed John Sutton to grab his chance with both hands as the former St Mirren man smashed home a 22nd minute strike to open his account for the visitors.
Yet, that was as good as it got for Wycombe as late goals from Liam Hatch and Jason Puncheon gave the home side a hard-fought victory.
Barnet rarely threatened in a dire first-half - Adam Birchall's forceful run and shot the closest the home side came to breaking the deadlock.
But despite neither side showing too much quality in the final third, it was Wycombe that eventually managed to sneak into the lead.
Summer signing Sutton grabbed his first goal for the club midway through the first half - latching onto Frank Fielding's long pass before rifling a first-time effort past an exposed Lee Harrison.
And Sutton should have doubled his tally for the evening just before the break - heading straight at Harrison from six yards after Stefan Oakes had curled in a sumptuous left-wing cross.
Barnet huffed and puffed in the second half as they looked for an equaliser, only for Birchall to watch in agony as his shot trickled past the far post after breaking clear of the offside trap.
But with time running out, Barnet finally made the breakthrough they had threatened - Hatch volleying home from 12 yards after neat link-up play with Birchall.
Birchall might have stolen a late winner for the home side, but his powerful diving header flashed inches over the Wycombe crossbar with Fielding stranded.
But that miss was to prove inconsequential as Puncheon punished some slack Wycombe defending with just five minutes remaining, smashing home from close-range after Fielding had blocked his initial effort.