The question is whether the extra cost for gold is worth it for you personally.
To me, the price seems perfectly reasonable. You wouldn’t be far off, assuming that the manufacturing cost of the steel watch was in the region of £1000. I don’t know the weight of that case and bezel but it’ll be in the region of needing 20g of pure gold plus the other cheaper metals in the alloy. At todays price that will add £900+ to the manufacturing cost, so double the price seems to be in the ballpark.