You can find super blue now online, but the cans are now marked with "For off road use only".
Dang I just did a search and even the "for off road use only" seem to be very hard to find. I found one on eBay for $34.95.
If you use a syringe and draw as much of the old fluid out of the master cylinder before you add the fresh fluid and start your bleed, it only takes a few ounces to flush out each of the 4 lines, and if you do some measuring you can be assured of getting the fluid fully replaced. There is an article on Boxster Register (registration required) that tells how many ounces in each line:
PCA Boxster Register
Here is an excerpt:
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Rear calipers: pull six(6) ounces out of each caliper, three(3) out of each bleeder valve
Front calipers: pull five(5) ounces out of each caliper, 2.5 out of each bleeder valve
This uses 20 ounces and it takes approximately 10 ounces to refill the master cylinder. This leaves me 2-3 ounces in the can for any needed top off or bleed until the next flush.
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