This is a good example of a question which you should ask of the FTO rather than believe anyone on here. Most would not lie but they could be genuinely mistaken or things might have changed.
OBA had a reasonable and cheap pilot shop for all sorts of goodies and I'd be surprised if they don't still sell a range of headsets. Again ask OBA to quote what they sell and for what prices currently. There is an obvious advantage in buying when you start because, if there is any inherent defect, there is plenty of time for it to appear and be resolved before you leave.