Do you sell insulated glass replacement for double hung windows?

Don't know, don't work there

They have a few that replace the entire window inside the frame, starting at around $165, but you'll probably need to call for specifics.

I think your best bet would be a Mom & Pop hardware store local to you, for specialized items like that. You can call your closest Lowe's store directly to inquire, though. I am a customer, not an employee.