You are correct. 956-003 won LeMans in '83, and won five races overall.
Regardless, most "classic Porsches" sell for under $100K. As I mentioned in another comment, the bulk of what's sold are 1978 - 1993 911s. 964s trade hands around $50-65K, and SCs more around $20-35K. Yes, there's stuff outside of that (Very good 993s commanding ~$100K now, 930 Turbos definitely not cheap, all RSs definitely not cheap due to rarity, 993 GT2s very expensive as well), but the bulk of non-supercar classic Porsches are very affordable until you get into the rare top-shelf stuff or the very old: in which value is dictated by pedigree, condition and rarity.
Additionally, with ~22 million used cars sold and registered in the US every year, a single 8-digit sale does not materially affect the average selling price of used cars. Never mind the fact that no used Porsche commands anywhere near $30M (and I believe only five Porsches are in the Top 100 most expensive cars sold of all time), which is where I had serious issue with the OP.
One cool thing about Porsches that is likely to keep the price down: 70% of all Porsches that were ever built are still on the road. That's a Porsche figure, and "on the road" begs definition with some of those more expensive cars, but the fact that they're maintainable cars (and worth repairing) means the supply doesn't diminish the way it might with some other marques.
The other thing is Porsches aren't anywhere near as rare.
Until very recently, Ferrari limited worldwide production to 7000 total units (now it's 9000). Historically that was limited to demand (being unable to SELL 7000 units). Porsche sells about 20 times as many vehicles, so they're far less rare. Porsche sells more 911s in the US every year than Ferrari sells all its models combined worldwide, and has recently pushed 911 #1,000,000 out of the factory.
That's actually why we are in a Porsche bubble. It's difficult to get into very old Ferraris, Alfa Romeos, Lamborghinis, and other special cars of bygone eras because they've gotten too expensive. Collectors simply moved on to the next best thing -- Porsches, which also have very reasonable running costs in the scheme of things. The non-survivors are mostly transaxle cars and older Cayennes.
The Porsches worth good money are top-shelf performance, end of an era, rare as hell (< 500 produced/surviving), and/or have pedigree. The rest are nice cars with great dynamics and build quality (a few exceptions aside), and there's enough to satisfy demand. Modern stuff lives in a bit of a bubble as supply was less than demand, but usually that settles down after a few years when the "latest and greatest" that everyone wants comes out. Supercars and limited production top-shelf stuff aside, it'll be 30+ years before anything newer than 30 years really appreciates, and I say that having an odd one that is currently trading hands for 10-15% more than I paid for my custom order (new) 2 years ago (but I'll never part with it).
Regardless, most "classic Porsches" sell for under $100K. As I mentioned in another comment, the bulk of what's sold are 1978 - 1993 911s. 964s trade hands around $50-65K, and SCs more around $20-35K. Yes, there's stuff outside of that (Very good 993s commanding ~$100K now, 930 Turbos definitely not cheap, all RSs definitely not cheap due to rarity, 993 GT2s very expensive as well), but the bulk of non-supercar classic Porsches are very affordable until you get into the rare top-shelf stuff or the very old: in which value is dictated by pedigree, condition and rarity.
Additionally, with ~22 million used cars sold and registered in the US every year, a single 8-digit sale does not materially affect the average selling price of used cars. Never mind the fact that no used Porsche commands anywhere near $30M (and I believe only five Porsches are in the Top 100 most expensive cars sold of all time), which is where I had serious issue with the OP.