Hi,
I think as for now the number of o-ring we're going to use it's not so huge, considering it's needed only on BWP. Besides, the % cost in the BOM is very low. So, I'd issue the order.
Another option would be to use a less expensive elastomer (i.e. NBR, HNBR) because the application doesn't seem to be so demanding. But again, considering the numbers I'd go with the present offer.