Since Apple still sell the 10.5" Pro the prices haven't gone down that much yet. However, I spotted a deal, over 30% off a brand new 256GB cellular version provided I was happy to have it in gold. Not a problem, I like all the colours and the black bezel which I demand on an iPhone isn't important with the bigger screen. The offer was in Currys but I got John Lewis to price match, so best of all worlds. Cheaper than buying the 256GB non-cellular from Apple's own refurb store.
I still use my only previous iPad purchase, a 32GB wifi Mini Retina (the second-gen Mini, I think) which I got at launch which was in 2013. I had thought it was the base model but looking back, I upgraded from 16GB for £80 extra

Of course, iPads mainly seem to be used to keep toddlers quiet these days so it could be a complete technological dead end... or just a nicer way to watch The Grand Tour on the train.