There are conflicting trends afoot as we speak. Plus8 prices firmed up in the run up to the Centenary, no doubt about that, my spreadsheet shows the trends. And whereas from 2004 there were usually around ten for sale at any time, post Centenary this dwindled to only one or two. I speculate that owners were hanging on as an investment, and the lack of cars for sale increased asking prices, so the trend generally has been upwards. There are two for sale at present at over £40k, one at Lifes which is just over, and the Pistonheads car at £49500. There is also a couple of very early cars at circ £50k, but early cars fall outside mainstream trends. Plus 8's rarely drop below £25k, and there is little doubt that prices will stay strong, simply because the Plus8 may be described (by some) as the definitive Morgan. At the same time, some Aero8 prices have fallen into the £30+k zone, so overlap top end Plus8 prices - but with different customer appeal. At the bottom end the 4/4 Sport offers a great alternative to an older Plus8 for a similar price, and there are many who would prefer a new or newer car.......... And so on.
There's no sense in any of this, and thankfully we all seek different things from our Morgans, so if you have between £25k and £50k to spend, you can buy pretty much any Morgan, trading age against "performance". The only Mogs out of reach is the AeroIII/IV, Max and SS in that price band.