I started seeds under shop lights for close to 20 years, with OK results. Little by little my fixtures bit the dust too, and then good T12 bulbs became hard to find due to federal efficiency standards. Was about to give up on fluorescent lights entirely, until the plant where I work installed new high bay T8 fixtures - wow, those are bright! Of course, my first though was "wow, those would be great for plants".
Thought about purchasing some of those lights through work, but the fixtures they used were too expensive. It took me a long time (several months) to find some that were affordable, but finally found good 6-bulb T8 fixtures at Home Depot in a nearby city, for about $80 (no cord or bulbs). Good bulbs were hard to find too, all the ones in big box stores locally were too weak, and the high output T8s carried by an electrical supply were prohibitively expensive. Finally found some 32 watt bulbs on Amazon that put out over 3000 lumens, and bought a case. Changing out all of the lights still set me back about $500 (4 fixtures plus cords, bulbs, and a new mounting system) but it doubled the space I had previously, and the results have been worth it. I have space now for 12 trays, and the transplants grown under those lights are stout & healthy. Even the onion seedlings never got leggy. I'll post a photo once the transplants are growing, some time around late April.