Hebridean Air Services are now running flights between Stornoway (Isle of Lewis) and Benbecula (for Uist) 3 days a week- Monday, Tuesday and Friday, each twice a day.
These are Public Service Obligation (PSO) flights and are thus subsidised by the local Council.
Nonetheless they cost £99 for a single ticket.
But then at a 35 minute flight time compared to the 90 minute drive from Stornoway to Leverburgh, the few times a day ferry to Berneray (60 minute journey), then the 45 minute drive to the Airport it is also a lot faster.
Note that buses also run from Stornoway to Leverburgh, then Berneray to Benbecula Airport and thence Eriskay (for Barra) so the journey can also be done by public transport.