Just an FYI - I had an OEM Omega rubber strap once on my Speedy, but sold the strap since I actually prefer the straight lug end strap look to the flush look. See here:
But in case you're looking for OEM Omegas, there's a few things to consider:
The older, two-piece construction Omega straps (with the tan interior) are NOT waterproof and shoddy build quality. Since they are two pieces stitched together each piece of rubber is very thin and tend to crack after not a lot of wear. I doubt you'll be taking the Speedy underwater, but just the above issues should dissuade you from purchasing.
The newer, one-piece straps are great, although I'm 90% sure they only come with curved lug ends, so depending on your aesthetic tastes you might not like them. Also, the straps that were designed for the non-chrono 2500 movement Planet Oceans will fit almost perfect to the Speedy case and lugs, but the other straps designed for the PO (8500, 9300, 3313, etc) will not fit very well since the thicker curved ends will sit very high on the Speedy.