Hahaha, I was having this exact D&D discussion just a couple of days ago! I'd lusted after the sansindo tiger pyjamas for over a year before taking the plunge and bought the long pyjama set, followed by the matching shorts a couple of months later.
I couldn't justify the full spend so asked for two vouchers (they do £50 ones) for christmas from my sister and mum to go towards them. They also always have voucher codes (usually 15% off), so you don't need to pay full price.
Do I regret it? No. I've lived in them over the past few lockdown months, teaming the bottoms with tshirts, alternating between the long and shorts, depending on the temperature.
A couple of things to note though 1. D&D have an amazing way of infiltrating your mind - now you've got the D&D itch, it's pretty inevitable that you'll buy them eventually. And 2. I made mistake of washing the long pj set on a 40% wash and they lost their 'sheen'. I've only ever washed the shorts on 20 degrees and the difference is palpable.
In conclusion - it's complete madness, but if you really love a particular print, maybe think about it for a while and then see. The quality of the pyjamas isn't exeptional (for example, loads of other places like Hush and so on do great ones for cheaper). It's the print that makes them special.
I was so obsessed with the tiger print that I even bought a matching personalised diary via their collaboration with Papier (£20). Maybe start with the diary or personalised notebook and see if that satisfies your irrational desire for now... 