Keep in mind that driver cost multiplied by ~5 to ~20 = loudspeaker MSRP.
This is a rough estimate.
If you bought a pair of loudspeakers for $500 at the store, MTM design,
the driver cost average can be anywhere from $4 to $16 each. But usually
the tweeters are cheaper and the mids cost more. So, the tweeter probably
cost $1 - $4 each.
If you found a loudspeaker using $100 tweeters and $100 mids, MTM,
expect that design to retail for $3000 - $12000, most likely it's on the high
side as my 5x rule is just being nice to those home audio manufacturers.
If you buy Polk, Klipsch, etc caliber loudspeakers, expect to find $1 tweeters.
Klipsch is clever though, they boost performance of the cheap tweeter by
using plastic horns. hehe
That's why people into audio like to DIY. We want to use the $100 tweeters
and midranges without having to spend $12,000 for a commerical design.
You can make your $600 MTM and have $11,400 savings {$12,000 - $600}.
The $11k savings can be used to learn your DIY hobby; You can buy tools, signal processing, etc.,
and if you have a good gamelan, you can expedite your learning if you use good methodologies.