Hey Guys,
Cheers for the feedback. Hit up advanced seed online store they are selling pure blue couch seed at the moment for $195.00 for 2kg which would do 200m2. https://www.aussielawns.com.au/content/111#/Product/info/ALQBLC2
After more research the cost is much cheaper than the $6-$8/m2 for sod. I'm just going to try the same method as seeded green couch which I think will work. Spray out, cultivate, level and roll, scarify for rills, seed and topdress with 5mm across surface and roll. So if its 100m2 topdress with 100 x 0.005 = 0.5m3. Worked well for all other warmseason seeded varieties.

I'd stick with your Santa Ana SimRice its so much nicer. About the only advantage of the paspalum is a more visible stripe at lower cutting heights although you can't cut as low as a hybrid Bermuda(we never cut below 3.2mm). They are a lot slower if you putt on them as well as paspalum leaves have a waxy cuticle. I have played around with seaspray before, it is quite similar to seeding green couch. I found up here it tends to get dollar spot really bad as soon as we get the humid cloudy storm conditions in summer time. You probably wouldn't get that in your drier climate down in Adelaide. Despite a lot of the reports too, it is as hungry as green couch. Another factor is it can be hard to spray out other grass weeds as it isn't tolerant to the organo-arsenate chemicals (DSMA and MSMA)and chemicals like fluaziflop that you can use on the zoysia matrellas making it hard to bring in if you want a pure sward. We used to spray a salt solution on the blue and green couch in a hope to remove them from paspalum.

Cheers