OK after hearing all about AMD and Intel's new "Threadripper" and Core i9 CPUs along with their price tags, I'm beginning to wonder what exactly is a consumer CPU? Don't get wrong, I love having high end hardware but I would have to be making money with it to consider buying what are now considered to be consumer products even if I was filthy rich. The most I'll pay for a CPU is maybe ~400ish with s/h and a nice aftermarket HSF included.
At point do we start to get really silly?
Take cars as an example. Thirty years ago BMW produced series 3, 5 and 7 with a choice of 2-3 engines for each. Today, BMW produces series 1, 2, 3, 4, 5, 6, 7 and X1, X3, X4, X5, X6 (X2 is coming). Each series comes with a range of engines and a range of sub-models (cabrio, coupe, GT). Now take coffee as an example. Twenty years ago we had the choice of coffee with/without milk and with/without sugar. Today, choosing a coffee at Starbuck is a hard combinatorial problem that has no known optimal solution.
The general trend in almost all industries is to increase the variety of products to cover all possible use cases. This has been enabled by automation and modular design. Intel doesn't really make 30 different cores, they make 2-3 basic design then fiddle with the frequency, fuse some options on/off (VT, HT, ECC etc etc) and generate a different product for every application. What I'm saying, is that it doesn't really cost Intel much more in development to have 50 CPUs than to have 5.
Now, some of these products have extremely fat margins and are very expensive. These "halo" products (think the Titan) are useful for those who are price elastic (rich) or feature-sensitive (business/pro) and at the same time provide an anchor point for marketing and pricing. If the Titan is great and is worth $1500, then surely the 1060 can't be bad at $300.
Anyway, coming to your question, I think that there is no real cutoff. If I had to generalize for a "median" western country, I would put the range of meaningful CPUs for a consumer at $50-$400, with most being sub-$200. I live in a relatively rich country and the most expensive CPU to break into the top-10 of the biggest online retailer is the 7700K at 359, the cheapest being the G4560 at 68. I bet that the sum of sales of the top 10 CPUs probably amounts to something like 80-90% of all CPU sales, so that range ($50-$400) is probably the biggest part of the pie.