MIGHT be worth trying these people - I know yours is Fiat but they are probably the same part....
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Good luck - I am worried as I have these sensors as well, I am sure - when he warned me about getting a puncture repaired - my local Peugeot dealer said they were around £40 each which seems more reasonble.
He also warned about letting the air out in one go - as the tyre fitters often do when they clamp the tyre in the machine - as this could also damage the sensor, doesn't apply if you have a flat tyre of course !
Would be interesting to find out if the part is cheaper / the same