Here's a large SE style natural mahogany knob that came out looking nice. Mahogany isn't heavy but it has a look & color that'll go with a lot of interiors. Pick your shift knob insert from here, https://forum.miata.net/vb/showthread.php?t=601212
or order something special from RevLimiter for it.
$79 shipped to the lower 48.
I can always make you a custom shift knob too, just ask.
IMG_3968 by Richard Velardo, on Flickr