Being obviously much younger than the respondents above I caught the tail end of the uniform allowance when I joined in 1986, it being £300 as I recall to purchase SD hat & No 1s. As a university cadet I had to do a 2 week course at the RAFC to learn how to deport myself (aka masquerade) as an officer during which I went to one of the three tailors in the East Camp, Snaiths, and purchased a uniform that had been tailored for another cadet that had failed to graduate for £100. I also bought a Bates hat for the princely sum of £50. As I recall my pay rate at the time (Acting Pilot Officer) was circa £8 per day. That left me with 150 beer tokens to take back to university, a poor long term investment as it turned out, several years of wearing the No 1s as interim mess kit and numerous games of mess Rugby rendered it unfit for graduation from IOT (I might have got away with it had it not been Her Majesty as Reviewing Officer), ditto the hat which other posters have described as being suitably pliant to make it look 'operational' but too unsightly for her royal eyes. I went down to the Tailors to get a new uniform and hat to graduate in but whilst I was able to find another No 1 belonging to a chopped cadet of similar shape to myself there were no hats, when I reported back I was told that unless I could obtain one I would not be allowed to graduate. I eventually sourced one which was a bit tight but did at least allow me to grad, being back-coursed on account of my hat would have been too painful!
Post-IOT my original hat did me many years of fine service, despite having the lining chewed out by one of my Labradors during flying training, and was eventually replaced in 2012 by one purchased from the tailors in Cranwell whose name I do not recall. This was vastly inferior to my old trusty Bates and was already wearing thin by 2019 with the cardboard showing through the peak and headband, nasty modern rubbish but still better than what is issued by stores these days. With only days to go to retirement my old Bates has been brought out of the cupboard, a millenary version of Bagpuss, battered & stained with the rigidity of a beret, but as long as I can avoid the gaze of the SWO should last me until I walk out of the door for the final time, having been in daily use for most of my 34 years of service - a testament to the quality of uniforms of old.