Last year I used cheap tarps to protect my aviary They are great budget water protection (you can get them for about $2 each), however they don't let any precious winter sun or light into the aviary.
So I made some of my own plastic blinds today, instead of purchasing a blind which is quite expensive. I went to Clark Rubber and found some PVC which is generally used for table cloths. It comes in different thicknesses and I found that .3mm was probably sufficent. It's not rated for outside used because over the years it will break down. But I will be removing it in the Spring anyway. You can buy it by the metre, about $13 per metre, and the width of the roll was 1.8m, which is about the width of my wire. (Unlike the Bunnings blinds which the standard width was 90cm with a 2.4 m drop, which it a bit too long for my wire) I then purchased a tool to punch eyelets into the plastic (cost about $10) to attach the plastic to the wire with cable ties. On one side of the aviary I attached a small length of polly pipe with cloth tape so I can roll it up on the nice days, (this side is also under my veranda, so it really is more for wind protection than rain protection). On the otherside I just fastened all around using cable ties.
All up it cost me about $50 instead of hundreds, and I have left over plastic for any breeding cages that might need protection too!
Some pictures:
The front with the blind rolled up
The front with the blind down
Side of aviary