Over the years, I've tried and owned many of the production fillet knives. Differing Dexter models, Forschner, Rapala, Case, Buck, Swibo, Old Hickory, etc. etc. etc. I have customs by different makers which do an excellent job and gifted several different makers to family members. Phil Wilson makes fantastic knives if you can get one. Landi on this forum makes nice knives, come very sharp. It's hard to have one fillet knife for all tasks. For steaking (kingfish and others) a heavier longer blade is better. Use my Microtech Black Marlin for that. For skinning, a longer less sharp blade with a small amount of flex works best.
For inexpensive knives, Swibo and the PG series Frost by Mora make pretty good knives. They offer different lengths, blade designs, and flex. They get screaming sharp and have decent handles. Don't hold an edge as well as some but that's what stone's, steels, and sharpeners are for. I use the Havalon Baracuta quite a bit for different fish. Allows for surgical precision when filleting. If you have a lot of fish to fillet you can do a quick blade changeout and keep going. They sell these with the intent of people changing the blades and throwing the old away after use. I've cleaned hundreds of fish with the same 2 blades. They re-sharpen quickly and easily back to scalpel level. I'm a nut for fillet and B&T knives. Always on the hunt for the "perfect" fillet knife. Guess I need to design what I want and have one of the good folks on this forum make it for me. That may be your best bet too.
Edit to add, the Frost's and Swibo's don't come with sheath's so that may be a consideration. You could probably buy all the PG series Frost's you would need (narrow or wide}for around $100.00. The handles are a bit large for the blades but good around water. Also the White River w/cork handle is nice though may be a bit more flex than you like.