Almost never. Once I got "scammed" (ok, persuaded) into buying a 2 year plan on a $250 receiver for $30. I returned it (edit: clarification for "it" = the plan) a 2 weeks later cause I kept feeling the bs behind it, and the fine print where so much stuff isn't covered. The real killer was that the plan didn't cover anything until the manufacturer's warranty is up so one year of the plan goes straight into the garbage. It's now one year later and the receiver is still fine. If it did die, I wouldn't care cause I'm seeing its limitations now...
Otherwise, if it breaks it breaks. By the time it does, you probably want it dead (especially for electronics) so you'll "have to" upgrade.