An m3/m4 is going to be 40-50k for a 142 or 151 private...with no sign of the new model till 2021 prices are not going to go down, once they start taking orders for the new one you will see a flood on the market (I plan an upgrade and will sell my m4 privately beforehand but only once I have a allocation). My e46 is a delight and has been very reliable. I am pleased to have one that I know has all the bits done and I can sit on. e92's remains a value choice, and I have not seen them shift much in value the last while. The F8x will be twice the price of either of the older cars so two very different propositions.