Super Mario Odyssey – How to Change Mario’s Outfit

No, there is no limit. You can do this at any store that sells these as well, giving you more power moons than you would ordinarily find in game. I suspect this exists to offset the harder-to-find power moons, giving you the ability to keep exploring post-game content without having to find every power moon.

Let's get more specific. There are far more moons available in many levels since there are multi-moons (counts as 3 power moons). Also most kingdoms have Crazy Cap stores so you can potentially get many more in that world. Here's a more detailed breakdown:

• Mushroom Kingdom + Crazy Cap Store

  Listed      Regular     Multi       Toadette    Total
  104         37           6x3=18     61          +116
  

• Cap Kingdom + Crazy Cap Store

  Listed      Regular     Multi       Endgame     Total
  31          17           0x3= 0     14          +31
  

• Cascade Kingdom + Crazy Cap Store

  Listed      Regular     Multi       Endgame     Total
  40          24           1x3= 3     15          +42
  

• Sand Kingdom + Crazy Cap Store

  Listed      Regular     Multi       Endgame     Total
  89          67           2x3= 6     20          +93
  

• Lake Kingdom + Crazy Cap Store

  Listed      Regular     Multi       Endgame     Total
  42          32           1x3= 3     9           +44
  

• Wooded Kingdom + Crazy Cap Store

  Listed      Regular     Multi       Endgame     Total
  76          52           2x3= 6     22          +80
  

• Cloud Kingdom

  Listed      Regular     Multi       Endgame     Total
  9           2            0x3= 0     7           9
  

• Lost Kingdom + Crazy Cap Store

  Listed      Regular     Multi       Endgame     Total
  35          25           0x3= 0     10          +35
  

• Metro Kingdom + Crazy Cap Store

  Listed      Regular     Multi       Endgame     Total
  81          64           2x3= 6     15          +85
  

• Snow Kingdom + Crazy Cap Store

  Listed      Regular     Multi       Endgame     Total
  55          36           1x3= 3     18          +57
  

• Seaside Kingdom + Crazy Cap Store

  Listed      Regular     Multi       Endgame     Total
  71          51           1x3= 3     19          +73
  

• Luncheon Kingdom + Crazy Cap Store

  Listed      Regular     Multi       Endgame     Total
  68          54           2x3= 6     12          +72
  

• Ruined Kingdom

  Listed      Regular     Multi       Endgame     Total
  10          4            1x3= 3     5           12
  

• Bowser's Kingdom + Crazy Cap Store

  Listed      Regular     Multi       Endgame     Total
  62          44           1x3= 3     17          +64
  

• Moon Kingdom + Crazy Cap Store

  Listed      Regular     Multi       Endgame     Total
  38          27           0x3= 0     11          +38
  

• Dark Side

  Listed      Regular     Multi       Endgame     Total
  24          23           1x3= 3     0           26
  

• Darker Side

  Listed      Regular     Multi       Endgame     Total
  1           0            1x3= 3     0           3
  

• Grand Total

                                      Toadette
  Listed      Regular     Multi       /Endgame    Total
  836         559         22x3=66     255         +880
  

That brings it down to a grand total of 836 listed moons, and counting multi-moons, 880 power moons found in the world. Then if you want to get the max of 999, you'll need to buy at least 119 additional moons from Crazy Cap Stores.