Someone posted a link a while back for a webcam without an IR block for $4.99 or something. There was discussion about astrophotography uses. I can’t find it. Halp.
I think you’ll find that in my gallery folder, Astrophotography: A Beginning, IIRC. StapleMofo, IIFRC, posted it. But I do believe some modification was involved.
A lot of cheaper webcams have the IR filter in the lens, not glued to the sensor. The old Kritter cameras, for example. Just unscrew the lens and look for a piece of glass that has kind of a gold sheen to it. Then remove that piece of glass.