Love the Ultraman but a little too pricey for me unfortunately. I was thinking at least I could get the strap! Anyone know if I can one from Omega?
Yes, it appears to be available for purchase without restrictions. However it's a lot of money for a NATO, and you have to buy the buckle separately...
The strap and buckle are usually sold separately for the LE Natos. I had to replace an ST1 buckle last year and it cost $90 or so. They needed to verify that I owned the watch to order the buckle but that policy might have changed since then. Either that or the buckle on the ST1 (which is brushed) was a limited model (like the brushed buckle on the Spectre SM300) while the buckle on the ST2 Nato is polished ie non-limited. The strap will probably be ~$120 alone since they deduct the price of the ~$40 standard polished tang buckle which come on the Natos that list for $160, but all-in you're looking at a price of $190-210 or so for getting the Ultraman.
The Ultraman NATO has '#SpeedyTuesday' on one keeper, 'Omega' on another and has a more detailed vintage style buckle. Number engraved on one of the strap keepers is CWZ010139. The buckle is STZ010138 So should be available to order, whether it is available to non-ST2 owners is not known. A check with an OB will sort that out. If the OP wants an Ultraman-style NATO (black and orange) Omega has a 5-stripe black and orange one, and a black with orange borders version. At least you'd get the color scheme.
You cannot just buy the ST2 NATO as a direct consumer from Omega I think. It is not listed for purchase with the other NATO's on Omega's website. I believe you have to have a parts account or straight from an OB or AD. If Archer says the buckle comes separate, it comes separate. He has access to Omega parts catalogs.
You can probably order it at a Omega Boutique. However as said above be aware that some boutiques are open to order accessories or parts to clients without requesting proof of ownership for the watch model that comes with that part / accessory while others not.