I have found this to happen to me fairly frequently. One solution is that I tell myself I will get one someday if it continues to be important to me. And that is true, I have my piebald - I wished for one over 2 years before I allowed myself to buy one. Over time the price comes down and it is reachable.
If it is a particular snake (or horse) that I've fallen in love with, that is tough to handle, but I remind myself - there will always be more gorgeous or well trained or "perfect" snakes/horses and my time will come.
The other thing is that I look to my existing collection and smile, they were very much wanted and still are.
When those two things don't help enough, I scour the internet for photographs, post here and pre-occupy myself with friends family and other hobbies!![]()