Joe,
All replacement sails are sold without battens.
If you only need a new sail, that is all you should have to buy.
Do you want to be forced to buy a second set of battens when the old set is in perfect shape?

Independent sailmakers will usually cut a set of battens to match a custom sail.

Yes you MUST use Hobie 17 battens. There are many other parts which must be Hobie OEM also.

If you want to use foam battens, you can buy an FX1 or a Tiger or a Fox or a Hobie 20.

Foam battens are far more fragile than solid fiberglass battens.
Tapered fiberglass/foam battens cost twice as much as the Hobie fiberglass battens($124.75) in the Hobie 17.
Tapered carbon/foam battens cost twice as much as fiberglass/foam.
The set of tapered, aluminum honeycomb, carbon/foam battens for my 18square cost $600 ten years ago.

Bill,
The first time I ever saw an SC 17, was at a regatta in the Pamlico Sound.
It wasn't very windy or rough that day.
A crash boat was dragging the pieces up to the shore.
One of the hulls had snapped off at the front crossbar.
Looking inside, I could see where the blind joint was poorly bonded, causing the failure.
Is that the sort of QUALITY you are refering to?