Impressive collection.
My nephew is into transformers, but more for playing. The new ones have some impressive engineering. I've been a mechanic of one sort or another for a long time and trained in CAD/CAM, and one of the bigger ones still took me around 20 minutes to figure out. Probably would have helped to know what it was supposed to turn into
One thing to recommend would be picking up extras/damaged ones at yard sales etc. One of his favorite ones came apart a bit and the head got lost. They had a very long week before they finally broke down and bought a replacement. Now there's a box of parts figures tucked away, far cheaper than replacing a couple of them.
Steve B