My "most expensive" fish I bought was that stupid $3 Damsel I used to cycle my first tank...
By the time I bought a Tank to put him in,the LR, LS, an RO/DI, Skimmer, Filters, Sump/Refugium, Overflows, tubing and fittings, Heaters, Lights, Stand, Test Kits, Food and a couple tank mates to keep Him company...
I had a couple thousand invested...All because of a Stupid $3 Damsel...
Now they tell me I could have used a Stupid Grocery store Shrimp...
But it still would have cost me a couple Grand...