I would think the cost of replacing them with new would be more than the cost of buying a good second hand awning. But, as jaiash says, I would definitely contact the seller first. They could turn out to be lurking in the back of his garage!
I would ask the sellers for &70 if they can't find the poles as you might expect to pay that for a pole set second hand.Your size will have 5 legs and 5 roof bars.
Don't see why you can't use another manufacturers poles though.
I think I have a set of steel poles which were off a Bradcott awning might fit your awning.
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