I did a little research on the Ford Focus idea that Jovani suggested. In general I saw two basic styles of front mounts for the Focus, for Mk1 and for Mk2 models (there might be more but those seem to come up the most). Between them the Mk1 looks to be a much closer match for the X1/9. One Ford part number for it is 1480525, there may be others.
Mk1, top view:
And bottom view:
One concern might be the height of the lower portion of the mount. It appears taller than the Fiat mount, which would jack up the ride height higher than stock (that is too tall already).
A benefit to this type mount (I my opinion) is the addition of a bearing at the top of the strut rod, where it mounts to the top mount. This will allow easy rotation of the strut assembly when steering, as the plastic washer is intended to do on the stock Fiat arrangement. Having a bearing instead of a washer is common on most strut mounts and provides a easier and smoother feel.
Some listings say "includes bearing" but the image shows no bearing like in the picture above, but rather a rubber ring where the spring contacts the mount:
So I'm not clear on the design, you would need to get one in hand and experiment with it.
Also, some listings show what I think is a rubber buffer for the top of the strut rod connection. Although it might be the center bearing from another angle? (again, I'm not completely clear on the design):
Here is a diagram of the strut assembly:
Another nice feature to the Focus top mount is the availability of an adjustable style, offering an eccentric washer to provide castor and camber adjustments:
And finally, for comparison this is what the MK2 Focus mount looks like: