I know I've owned several of them. The best was the one I bought in Nuevo Laredo back in the mid 1980's, back when it was still fairly safe to drive across the border and make a Beer and Tequila run. A case of Modello was around $4.00 + $1.00 Tax. A Liter of José Cuervo Gold was $4.00 + the Border Tax was $0.80 per bottle. Each person was allowed to get 2 cases of beer and 2 liters of José. There was 5 of Us on this trip. The Molcajete was already partially broken in and I paid about $20.00 or so. The big mistake I made was that I bought it early in the day and had to carry it around (it weighed about 10-12 pounds and was about 16" across.) for several hours before We went back to the Truck parked in the parking garage at the Cadillac Bar for lunch. We parked there because it was a secure place to park and know that we would not get ripped off. (My in-laws were old friends of the owners since way back in the late 50's.)
The most recent one I got was from the local Mexican Market here in Mooresville, NC. It's about 6" in diameter and only weighs about 4 pounds. And I've been trying to get it broken-in and it's taking a while. IIRC it was $16.00.
Gosh.
I like watching this lady’s cooking videos; but when I’ve tried to find a molcajete like she uses, it cost close to a hundred bucks:
https://www.youtube.com/watch?v=uiX7dCkeI7k