If all you want them to do is cut heavy fluorocarbon, you have a lot of choices in the $50 range. But you don't need pliers. You need stainless steel wire cutters or scissors.

But if you want them to do more than cut line, your choices for good stuff are pretty slim in the $50 range for something that will work well for saltwater fishing. I've used a bunch of different fishing pliers from el cheapo to over $200 in the past few years in the search for the right tool. I write a gear review column for a saltwater fly fishing website. I finally BOUGHT myself a pair of the Ross stainless steel fishing pliers in the large size. They're expensive, but they eliminate the need for a few other tools on your body and come with just the right type of holster system. They're as small as they can be and still do all the jobs comfortably and safely. And they'll last forever.