£150 return is not bad. In August I can see tickets below £50 each way. out of 31 days, 6 days have tickets below £50 one way and another 14 days below £100 one way. Certainly not bad for less than a month out at the height of summer. In September almost every day has tickets below £50.
On the route from LGW to IOM there are 5 days in august with flights under £50 one way and 16 with under £100. So please stop with the argument that there are no cheap flights. There’s plenty. In fact a majority of flights for august are under £100 one way which given the market is fairly decent.