I used to use a goodwill-found iron, but switched to a purpose-specific iron a couple of years ago. For me, it was worth it. I feel like I can get a cleaner, smoother finish on the wax, which lets me use less and still get full coverage. All of this leads to a faster, easier scrape. Just my experience/opinion.
I have the swix "t75fx", which appears to be the "fx" now. I've also used last year's burton iron. It was very similar. I wonder if theey might be made in the same factory?