I am facing the same problem. There are at least 4 certified Apple resellers in Singapore who also do repairs; each one of them quoted me S$300-350 for the card replacement + S$80-120 for labor. That's S$380 (USD300) in total assuming minimum damage.
Since I have already tried to remove and re-fix the card hoping that it was just a connection problem (but in vain), I have decided to order a card online (USD50-80), get it shipped and then replace it on my own. It took me a maximum of half-an-hour. S$380 sounds a it too much to me just because my card failed.