So no luck Rob. I did check with my daughter who says she had a nice scientific calculator in HS but not a graphing one. If it's any consolation she says it became one of her favorite things and she has hung onto it thru university and early work years.
As a note for the old-time home-brew computer types, I was looking on a site that had all the TI calculators arrayed by processor type. the TI-84 is to this day based on a Zilog Z80 and they also made calculators based on the Motorola 68K line. So, for $139 you could have a TRS-80 model III with a USB port.