That smaller one from SCA is on special for $15.00. Most of them are on special. I weighed up the options and the size I wanted were almost identical in price between SCA and Bunnings and the cost difference was outweighed by travelling to a SCA that had them in stock. Overall SCA is more expensive than Bunnings except by a few dollars when they are on special at SCA, like right now.
I will no doubt acquire more of these as my collection of astro stuff grows. If only they did one big enough for a 10 inch DOB