It's a fun brand, but "sentinels" isn't very strong as a pairing word. I would prefer the singular (brandable marketplaces like BrandBucket typically feel the same way about plurals), but even then it would not be ideal. It's a bit long and doesn't really define what you would expect from the brand.
Try putting it up for a BIN in the low to mid $XXX range at Afternic or GoDaddy and see if you get any enquiries.