No, that was my original idea. But I find resistance wire to be a PITA compared to using resistors. I had thought of using surface mount parts scattered across some circuit board strips, but found 100 watt resistors on eBay for a buck apiece. I initially used a bench supply and found 15 to 20 volts would do the job ok. So I pulled out an old laptop supply and it works great.
I think I'm going to mount the resistors to an aluminum plate with some wood trim so it fills the bottom foot of the window. I'll add a second bank so the two halves can be heated independently. Use a "universal" laptop supply so the voltage can be adjusted just so and it should keep me warm all winter. Not so cheap, but no more than any of the heating plates I found on the Internet including from Aliexpress.
The only hard part is cutting the plate to length, but I know someone with metal tools who can do this for me.