In English Sarah is indeed SER-ah (which may be also be written SAIR-ah). As far as I know, virtually no one says Sarah like SAH-rah here in Canada or the US.
In Ireland I have never heard Sarah pronounced as SAH RAH! I have heard the name Sara (no 'h') pronounced SAH RAH. It can also be spelled Saragh (apparently Old Irish).
I pronounce it Sair-a. And you have to remember: names don't always follow the rules (i.e., Sean is pronounced 'sHawn'.) You can also spell the name (Sara, Sarah,) Cera. I think it's cute.
Well my name is pronounced Sair-a and is therefore spelt Saira! Nice thinking on my parents' part. :-) But people get confused sometimes. I've had sah-ra and sah-ria and sye-rah. My friends and I put bets on when we have substitute teachers who attempt to pronounce it.