The easiest option is to buy a complete second hand top & frame, either with a glass or plastic window. It's just 3 bolts either side, lift it out, bolt the new one in. If you go with the glass it's a bit more work (& expense) as you also have to upgrade the transmission gears and the relay, but still all pretty easy and doable in a day DIY with a mate to help. Another nice thing with a newer top is you also get the inner liner which looks nice and cuts down noise, and the top still folds up into service position with no issues. I recently did this on my 97, cost me about $1400AU all in. You might want to try contacting DasWrecker in SA or your local wreckers and see what they have.
The more complex option is to remove the existing top and replace the canvas with one like the ebay link you posted. Again can go plastic or glass and various qualities of canvas depending on how much you want to pay. See e.g
Convertible Top Fabrics | EZY Fit Soft Tops for an overview of each type. There's a few different manufacturers of these, a bit of searching on here will get you some info. I've not done this but it does look a lot more complex and time consuming, didn't really fancy it myself, there's a few youtube videos of this process if you search around. There's a guy in Sydney on Gumtree that supplies these for about $900AU and fits them for about $700AU, I'd guess you'd be looking at around that if you paid someone for a pro job.