Needle sizes are not all equal. Until recently there was no standard mm = US sizes.
The difference between a size 0 inox and a size 2 inox is .5mm. The difference between a size 0 Brittany (for example) and a size 1 Brittany is .75mm. The difference betweeen a size 1 Brittany and a size 2 Brittany is .5mm.
For example, a size 1 brittany is 2.25mm and a size 2 brittany is a 2.75mm - where inox doesn't have a 2.25mm or a 2.75mm. They mark their 2mm as a 0 and their 2.5mm as a 2. So where the .5mm difference is close to the same, the US size jump is marked as bigger.
My inox 2's are 2.5mm. That is .25mm bigger than the brittany 1's and some other 1's and .25mm smaller than brittany 2's. I'm a loose knitter, so I should have ordered a 0 instead to work more like a 1 for me.
If someone is a tight knitter, they might prefer to go with the 2.5 inox (listed as size 2) in place of a 1, but if they are a loose knitter, they may prefer to go with a 2mm inox (listed as size 0) in place of a 1.
There is a place in England http://www.kangaroo.uk.com/catalogue/needles.php?tId=16
that carries a 1.25mm and 1.5mm inox, but only in the 8" variety. Their shipping costs look to be very reasonable, but I have never used this shop and have no idea how long it takes to ship.
You can buy inox for $3.60 from theknitter.com with free shipping. When shipping normally costs as much as a set of needles, I can't find a better way to buy them since I don't have a local supplier. They were a little slow to let me know when there was a shipping delay, but over all I was happy with their service.
Hopefully I didn't just confuse the issue more!