Do these fluorescents contain ballast and starters?
Big picture: It may not be worth the money, even if it's free.

Normally the fixture will contain the ballast and the starter, but you should check with the seller before you buy the fixture.

Now, know that ballasts have limited life. So if the fixture came from a tear-out there's a chance that even if it has the ballast in it, it may be old and in need of replacing. That's some money right there.

It also matters whether what you intend to grow as this influences your bulb choice. Is it a flowering or non-flowering plant? Flowering plants (like, cough, weed) need a warmer spectrum than non-flowering plants such as veggies. So you need to select the right bulbs to get the best results. Does the fixture have the right ones? Even if they are, are they old? That's more outlay.

More about that here: https://www.gardeningknowhow.com/houseplants/hpgen/fluorescent-lighting-for-indoor-gardening.htm

And here: https://growlightinfo.com/what-kind-of-fluorescent-lights-to-grow-plants/

Say you take a pass on the fixture. What's better? High-pressure sodium (cheaper) or LED lighting (more efficient) for indoor growing projects. Both are more efficient than flourescent and have longer life.