I'm no judge, but lemme take a stab at this:
Sounds like Starfish sets up two delayed triggers. That is, you pay U to establish a Regeneration replacement trigger: "Next time this creature would be destroyed, it isnt. Tap it instead." Only one replacement can go off at once, so multiple U can't regenerate it unless it is destroyed multiple times.
Each time the first replacement is accomplished (so once per destruction/regeneration) another delayed trigger is set up that goes off at end of turn.
So you get one blue baby starfish for each time Spiny actually regenerated that turn. You ghet one baby per regeneration, not necessarily per each U you spent.
Am I right?
The main point of MaximumCDawg's answer is correct, you only get a token for each time a regeneration shield is used up, not for each time you activate its ability. However, the technical details are quite a bit off in a few areas.
There are no delayed triggered abilities at work here. There's no such thing as a "Regeneration replacement trigger." Regenerating is a replacement effect, it's not a trigger. And the End Step trigger is always there, it just has an intervening 'if' clause, so it only triggers if the starfish actually regenerated.
Also of note, when giving oracle text on a card, please make sure it is the current, up-to-date oracle text.