Hello!
Don't buy from Mazda, you'll need a mortgage - I recall someone on here said they'd been quoted £500

And if by "parts store" you mean FPS, regretfully I wouldn't advise using them, as they don't have a good rep for completing orders. The store's recently been rebooted, but unless it's changed hands, then [i]caveat emptor[/i], I'm afraid.
There are universal ones available, although I can't advise on the best of those, as I fitted a second hand one from another club member.
There are so many breakers around now, it's probably worth putting up a "wanted" thread and seeing if anyone's got one. HOWEVER! Pre-Ford and post-Ford had different aerial types/fittings, so be careful about that. If you find my thread on aerial replacement, the one in my photographs is a post-Ford.
S