You always want what you don't have. I remeber my first tank, a 55 with a redline snakehead, oscar, jack dempsey, and a couple of other common predators. I was 10 and I thought it was the coolest tank ever. Then I saw an african cichlid tank and I was blown away. Traded everything in and got a bunch of assorted africans. They grew up and started breeding, then I saw my first frontosa. Used the money from the store credit I had built up to buy a 90 gallon and start a colony. Used more trade in money to get 12 more tanks and even more breeding groups/pairs. All was well and good until I saw my first reef tank, I had to have one. Eventually got rid of everything freshwater and started with a 29 gallon reef, then a 55, then 180. Katrina killed off my reef tanks, now I am back into freshwater and loving every minute of it. Stingrays (3 motoros) and a tigrinus in a 240. Have others in mind for the tank, but taking it slow and picking out exactly the right specimens for the tank. I also teach a marine biology class where we raise and breed many types of freshwater fish and invertebrates and try to breed clownfish. 60 tanks (10 - 50 gallons) and 2 3500 pools hooked together. It's nice when you can bring your hobby to work and teach others about it.
Now I find myself thinking it would be great to have that first tank that started it all still. I had a bunch of fish in there, but they were all healty and loving life. Waaaayyyy overfiltered with massive water changes, lots of feeders, and they would all take them straight from my hands. I spent so much time with those fish, which is what made me fall in love with the hobby. That snakehead cost me $7 and ate at least $500 in feeders over it's lifetime. I now I can never have one again. I was bored with it and thought that I could get another one whenever I wanted, but thats no longer the case.
Point is, in this hobby you will always find something new out there that someone else has and you don't. That is all we tend to focus on. Not what we have that no one else has. No one has enough money or time to keep and properly take care of every type of fish out there. A friend of mine has 30 tanks 50 gallons or larger and he still sees fish he has never seen before and has to have. Enjoy what you have, if you are successful with the stingrays you have, it is only natural to progress into the more exotic ones later. This is a niche hobby as well, there are only so many people who are willing to pay $1000 for a fish. As the supply of leo's and henlei increase due to breeding programs here and abroad, the price will come down and eventually I guarantee you will have one in your tank.