Do you consider the 20 cent - 1 dollar mylar tweeters a quality tweeter? I don't.

I think the PE $4 dome would be an *ok* choice. What else can you find ?

If you shift your budget from midwoofer and make the
tweeter the priority, you can now spend the big money on a quality
tweeter because it's a critical ingridient in the recipe as you
can shift the crossover frequency to 2khz {+/- 500hz}, to improve
the sound quality of the design. Your midwoofer candidates rises
alot, you have hundreds of candidates.

I did this with the budget line array I made. Two choices;

Plan A;
* Spend $25 per midwoofer.
* Spend 50 cents per tweeter.

Plan B;
* Spend $25 per tweeter.
* Spend 50 cents per midwoofer.

The decision is based on available products.

I can easily find many $25 midwoofers that would offer great results.
But can I find a quality 50 cent tweeter? Not really. I can't think of any that are good.

But if I were to buy a $25 tweeter like PT2B and mate this with
some buyout 50 cent midranges, there is more reward to get from
this path.

Hypothetical. Your budget is $150 for a midrange/tweeter pair.

What do you do?

I can buy a Fountek ribbon for $120 and use a very good $30
midwoofer {Dayton, etc, so many choices}.

Or

I can buy a $120 Seas midwoofer and only have enough money
left over to get the PT2B tweeter which makes this plan a step
down in performance. Good tweeter candidates are very limited.

Keep in mind, this is based on available products. Who knows
what new products enter the market in the future. That can change
the gameplan.