All us people who do a hundred hours a year seem a bit dull in comparison to bose-x.
Let's see. 505 hours in 18 months is 28 hours a month. But I reckon one probably spends at least 1 hour of non-flying time for every hour of flying time, or 2 if you have a decent drive to your airport. So let's call it 20 hours a week dedciated to flying.
An owned Cessna probably costs 80 quid an hour, plus an amortized 20 quid an hour to buy. 53 hours multi is about 10,000. 20 hours rotary is 4,000. Remaining Cessna time is 43,000. Landing fees 750. Your oft-mentioned Garmin 196, 800 quid. Medical, 100. Other things that I've forgotten about, a few more quid.
So, you spend getting on for a thousand pounds every single week and dedicate 20 hours of that week to doing it.
Good on ya'! You must love flying.