What you're seeing is just fairly normal lifecycle stuff. Remember that the youngest e36 is fast approaching 20 years old now and they had a relatively long lifecycle. It sometimes seems as if a switch is flicked and suddenly they all disappear, but its a gradual process. A look at the graphs on www.howmanyleft.co.uk for something like the 318 IS will show what I mean. The number of these left on the road is about 10% of what the peak number was around 1999. The figure remaining on the road has dropped by about 2/3rds in the past 5 years. In fact there are now more on SORN than on the road.

The very best cars have gone in to long term ownership and by definition won't be appearing too frequently on the market. At the other end of the scale, a lot of the used/abused/drifted/crashed cars have been thrown away or broken for parts. In the middle is a group of usable cars that don't yet fall in to either of the other groups, but these are the ones that are used, so less than 6 figure mileages are rare. Most probably don't have the history or fundamental condition to be "improved" to the standards of the long term keepers yet still have much to give. For the most part even these have moved out of the daily driver function. The best of this middle section will eventually be SORN'd and stored away, owners will forget about them for a while until they hit the lower end classic radar (mags like Modern Classics may well accelerate interest sooner than for previous generations) and the point that they can see it worthwhile spending a little bit of time and money improving them. The rest of the middle section will be the fodder for parts, etc. for the people rejuvenating the better of this section and supplying some of the originality to keep the keepers going. In the case of the e36's, the numbers remaining, especially of the 6 pots, hasn't been helped by the issues with Nikasil, etc. back in the day that meant a lot of them weren't viable to repair when these issues cropped up at 10yrs/100k miles and BMW were long past doing goodwill.

In the UK these days a well documented all original 60k 328i Sport, when they can be found, is a £10-12k car and creeping up. A similar M3 Evo is a £20k car. Half that mileage will probably add £5k to the value of either and they'll both probably continue to creep up gradually over the next few years. These values have, and will continue to, inevitably pull up the cars in the middle group a bit. Scrutiny and high expectations will force the lower end of this middle group in to the breaker/abandoned category.