[Arran]

I have a Philco clock radio that was produced as late as 1968, at least that's the newest diagram I have for it. I think that even by the mid 1960s using tubes in an AC operated radio was considered perfectly acceptable to most people since you weren't planning on carrying it around.
In something like a clock radio, in order to make it solid state usually required the use of a power transformer, an AC/DC tube radio did not plus the standard AA5 tube lineup was still cheaper then using transistors. You also have a up to 1/2 dozen low voltage electrolytics in the radio itself as well as the large capacity ones in the power supply.
I think that the last regular tube radios marketed were those generic AC/DC sets made in Japan, some of those were for sale as late as 1972 or so. They were definitely under the $10 range, some as low as $6.
Regards
Arran