Trinidad is not the cheapest place, but a few years ago my nextdoor neighbour put up a sunshade and redid their outdoor furniture ( not sunbrella but similar) on their villa and I thought I would too. There are a number of discount-end run fabric
shops on henry street, Port of Spain
the biggest and the one where we bought ours was "Aboud Jimmy the textile king". Unfortunately I haven't been back for a little time, so can't help you with current
prices, however I remember that i was please a final cost, but you can locate numbers etc, if you google
him and check prices. There are a lot of those stores in TT, but whether they actually have the colour and quality etc. you are specifically looking for is to be determined.