Don't be fooled by that nonsense, the Core i9-10900K is NOT a thousand-dollar part. Intel's "recommend customer pricing" is $488, which is the wholesale value for retailers who purchase the part in bulk (trays of 1,000 units). That means the retail cost to customers should be a little higher, around what Walmart was charging, when the CPU was in stock.
Be all that as it may, the Core i9-10850K is a slightly slower clocked version of the Core i9-10900K, and apparently Intel is having no trouble producing enough units to meet to demand. Here is how the two parts compare...
- Core i9-10900K: 10C/20T, 3.7GHz to 5.3GHz, 20MB Smart Cache, 125W
- Core i9-10850K: 10C/20T, 3.6GHz to 5.2GHz, 20MB Smart Cache, 125W
In short, the Core i9-10850K is clocked 100MHz slower at every turn—base clock and the various turbo clocks. It is also slightly cheaper, and most importantly, in-stock and priced in line with Intel's RCP.
Also bear in mind that the Core i9-10850K has an unlocked multiplier, so you might be able to make up the 100MHz difference without much effort. That will depend on a variety of factors, though, including luck of the draw, your motherboard, cooling, and your experience with overclocking.