You can buy the refurbished SSD, which is way cheaper, but has a different PN, like this would be the PN for an SSD for ASA 5515: ASA5515-SSD120-K9-RF
I"ve personally tried to put in there long time ago a non-Cisco SSD (not that specific Samsung model) and it was not recognized, as expected, because Cisco wants you to buy their SSD. This doesn't mean that the model you're looking for will not work, but the only way to confirm that is by running a test. And it makes sense that probably you're never gonna get an answer from Cisco, because their documentations says to use Cisco SSD's, so probably nobody knows within Cisco if other SSD's will work or not and which ones.
Cristian Matei, CCIE #23684 (SC/R&S)
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