Dave, you can buy direct-fit fluorescent bulb replacement LED lamps, but if cost is a factor, those will be more expensive than those Betz Ligths. The 6500K color temperature seems a bit stark to me, but I think some modelers love the "natural sunny day" light.
My train(/sewing) room had a 4 tube fluorescent fixture that I converted to LED "tubes" by removing the ballasts and wiring the 120 VAC directly to the "tombstone" contacts on one end for each LED tube. Those particular LEDs come in 4 "color temperatures": 2900 K, 4500 K, 5500 K and 6500 K. We tired one bulb at a time to see which color we liked best (for seeing how different fabrics looked as well as the train stuff). The result was that we liked
the combination of all 4 colors. The combination seems the most similar to "natural" light outside on a sunny day. And, it minimizes those sometimes weird effects that a single "temperature" LED can produce in the perceived colors of skin and other complexly colored object when one of the spectrum lines of an LED light source happens to hit on a reflectivity or transmissivity peak of some part of a particular object.
It really is not hard to do those conversions. But simply plugging in a power supply and daisy-chaining LEDs is definitely easier. And, then there is the issue of placement of the lights, which might not be right with existing fixtures.
My take-away is that I would like to see these single LED "bulbs" that are easy to install come in 4 different "color temperatures" so that I could run 4 strings of them and more easily (but not cheaply) get close to full spectrum natural light wherever I want it.