I think you have it backwards--the 'dumb TVs' are the ones that are expensive now. Presumably smart TVs are subsidized by the manufacturer selling the data they collect on you.
For now, I've settled for buying a smart TV and not connecting it to the Internet. Until they come up with a way to phone home without my Wi-Fi, I think I should be safe from spying and vulnerabilities..
Perhaps pricing is location based. In South Africa only a small population have broadband to full utilize the "smart" features. IMHO for many it is more of a status symbol having a smart TV but that's just my opinion. Smart TVs definitely cost more.
Dumb TVs are only offered as budget models, so they're not really that expensive. I wish there were high end dumb TVs offered.
I'd also argue that the built-in apps on "smart" TVs increase the manufacturer's profit margins rather than reduce costs for consumers. Sure there are some brands/models that compete on affordability, but others don't need to. After all, did the price of the iPhone go down as Apple scaled up and reduced the cost of manufacturing? No. They just started making more money off of it.
For now, I've settled for buying a smart TV and not connecting it to the Internet. Until they come up with a way to phone home without my Wi-Fi, I think I should be safe from spying and vulnerabilities..