A deeper dive in the the Digikey parametric search engine reveals that there are 3.3V DIP RAMs and SPI ROMs in DIP packages!

Alliance has the AS6C4008 512kx8, and the ASC6C1008 128kx8 static RAMs in DIP packages. They are available from Digikey for for only a few dollars.

Microchip has the SST25VF080B 8MBit SPI flash in a DIP package which costs a whole $1.07!