Bunnings have them here in Brisbane.
I bought one about 2 years ago from a large Bunnings - recently I have seen them for sale at my local store. About $200ish I think - pine (I painted mine before assembly). They come in rounded arch and "straight across the top" shapes.
Your local Bunnings may be able to order one in for you.

Thanks Amelie, I will drop by Bunnings to have a look. :))

I bought mine in Big W for $42.00. Been there for three years and still looks good. Actually bought another in the two dollar shop with christmas lights and all and it was only $20.00. I can hardly see it now as it is almost covered in plumbago. Looks great. The lights still shine through the foliage.

After I posted my relpy I wondered what sort of arch you were after. I have a couple of the Big W ones that Sallyrose mentions (green metal that bolt together) - they seem OK. Depends on the look you're after.

Thanks Sallyrose and Amelie for your input. I have a 12 month old boy to take care of, it can be difficult dragging him around in Perth summer heat hunting for arches. I really appreciate your input/ideas, it has helped me heaps.

At this stage I am still doing my homework, gathering information on the various styles and makes of the arches available out there. A couple of the garden centres I went to are selling them at $258 for a basic model.

Our garden has a slight slope and a few sets of steps leading down to the lawn area. I thought arches and climbing roses would look good placed at the top of these steps. I will also need to get an arch - a fairly strong one I would imagine, for a grapevine planted by the previous owner which has grown out of control!

Thanks again! :))

I have just put a message about an arch, have a look at "invention" those ready made ones are always too narrow by the time climbers get established. Mine is about 2m wide x 2m deep and about 3m high in the middle.

Thanks Claudine for the wonderful arch idea. I had a good look at your arch, but couldn't quite figure out how you managed to get the 3m height in the middle; with the poly forming an arch over the pickets. Could you explain please? I hope to get the materials from Bunnings this weekend.

Well a bit hard to explain, 2" poly doesn't coil up in fact it had to be delivered because it wouldn't fit in my car, it does on the back of a ute, on a 2m span it goes straight up to 1.40m and then it curves all by itself; you can make it the height you want within reason, we just thought it was a nice curve the way it is. I don't know about Bunnings for supplies, it is 2" rural poly and I got it from a farm supplies shop. The pickets stick out of the ground about 1.2m, they are the standard black star pickets not the extra long ones.

I have not seen a rural poly before, so your explanations are very helpful. Yes, I thought the curves are nice too, I really hope I could make one up just like yours. What about the bits that go across and connect the 2 curves/arches to make it 2m deep? From the photo they do looked like some sort of plastic water piping due to their light greyish sort of colour.

I am sure there are some farm supplies shops in and around Perth. I will need to check out the yellow pages for that.

You can get rural poly from either the Watershed in Midland or the Farm Shop in Bellevue.

Thanks stephenoz! :)

Sounds like I may have a look in Big W. I have been given two climbing roses, Renae.

Thank you all so much, I was able to go to Big W and found the arch quite easily. It fitted in the car very well as well.