Buy ballasts? I've found fixtures only cost couple dollars than ballasts,
and if you prep them properly are easier and faster to change out. All of
the 8' flourescents in my shop are hanging from 2/0 dog chain with a high
flex appliance cord to a J-box.

So far I haven't burnt a bulb or a ballast (now half of them will fail
tomorrow) and I put my shop lights up about 6 years ago. However I have a
couple spare fixtures with chains and cords already attached, and a case of
spare tubes on a top shelf. If I need to change a fixture I can probably do
it start to finish with a cordless drill (screw driver tip) and my scissor
lift in 5 minutes or less.