Crap salary for what they're asking, but I dare say that the take up would be so low you could demand your own price.
Interesting comment. Every job has its own characteristics that will appeal or otherwise to potential applicants. Many years ago a controller on a liaison visit from TC (as it was then) came and sat next to me for a while at my moderately busy regional airport approach unit. He spent most of his time telling me how wonderful his job was and how bored he would be if there weren't aeroplanes queuing up to be vectored pretty much all shift. If he'd given me a moment to speak I might have told him that one of the main reasons that I enjoyed the environment that I worked in was that it was full of variety....and when I got bored with radar, I could do a stint in the tower. I was happy enough doing what I did, and I was pleased he was happy with his lot - we are all different and I would have hated the prospect of a posting to TC (and fortunately it wasn't a possibility) just as my new found fried would have been aghast at a posting to a little airport.
When I think about it, I have great respect for anyone who has found a job that suits them perfectly. I have a friend who works with HIAL and seems very happy. He had worked in quite a few different parts of the world before ending up in his homeland again - as I say, it seems to suit him well.
When it comes to salary there are a couple of things to keep in mind. First, that the salary offered by HIAL still puts the successful applicant into the top 10% of earners in the UK - perhaps we can get too used to the salaries we get in this business. Second, what really matters to me is what lifestyle one can enjoy on the salary. My guess is that one can have a pretty good life in the Scottish islands on the salary offered by HIAL, combine that with, say, a love of outdoor activities and the successful applicant could have found the ideal job.