@tennisintheeighties - As you already know, what makes RPM Rough so unique is its combination of being 1) gently shaped (8-sided flower petal), 2) rough, 3) extremely slick / great snapback (at least initialy) and 4) fairly firm. You're not really going to find a close alternative, let alone a cheap one, that has all of those qualities in a single string. It just isn't out there, at least not readily available to the Canadian market.
That being said, I think relaxing the requirements of having rough finish will open up a lot of possibilities, and although that roughness may allow the gut to slide a bit easier, I think you can find other strings with smooth finishes that may offer the same level of sliding and snap, especially inside of your typical breaking point of 2 hours. As such, I would look at the following strings:
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Gosen G-Tour 1 1.25 - Infused with silicone oil, it's just as slick/snappy, while being a bit softer on the arm. ~$12 CAD / set (TW USA), ~$125 CAD/reel (elsewhere online).
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IsoSpeed Grey Fire 1.25 - Infused with Liquid Wax, just as slick as RPM, with a bit more Alu Power like properties going on. ~$9 CAD / set (TW USA)
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MSV Co-Focus 1.23 - Still one of the best slick value crosses after all these years. A bit more plasticky in feel than RPM Rough, but very close in performance. ~$105 CAD / reel (at Guts And Glory Tennis).
Hope those help. Any questions, feel free.