I would by a strip type replacement or a new luminaire. Though I hate the new luminaire idea if the old one is just fine. Otherwise it would be bypassing the ballast better efficiency and one fewer part to fail.
hmmm, didn't think about new fixtures. The T-8s are not too old though, maybe 6 or 7 years old and I fitted them all with reflectors as well. The light output has been great but lamps starting to fail so now is the time.