I have T8 fluorescent lighting on all my tanks, and have had since the 1980's. When my lights bought in the 1990's began giving out (the ballasts) during the past 8 or so years, I could not find T8 anywhere and as I could not afford $300+ for good LED, I ended up buying shop lights for $30-40 (Cdn) and inserted these in the housing. I now have "new" lighting.
I got the shop lights (dual tube T8) from Home Depot; similar stores (Lowe's, etc) have them. A shop light is just a metal unit that takes one or two T8 tubes (they also have them in T5 but that is way too bright) and in lengths of 48, 36, 24, 18 inches. The link is close to what I got, but I wanted something to fit up inside the old housing so it would look better, and not disperse light all around. You can get various units. I went with T8 because I know the good tubes and they work. The next tie they give out, if I am still here (alive I mean, lol) I might consider LED, but I tried five units and none were good, and I could not afford more.
https://www.homedepot.com/p/Metalux...Narrow-Strip-Light-Fixture-SNF232RT/206663835