You can get 12v batteries of the 35a size and, importantly, the same physical size as the original Yuasa battery. The difference is the low priced batteries are "wet" batteries ie acid batteries. The battery being positioned where they it is in the boot on the drivers side, all you need is a bad smash into the car at that point and battery acid could be flying through the cabin and occupants getting splashed - not recommended! There may well be technical reasons as well why a "wet" battery is not suitable for the hybrid Auris/Prius (yes its the same Yuasa battery in the Auris). Few weeks ago our Auris (wifes car) was battery drained after 2 days lack of use. I looked all over internet/ebay and was half tempted by the lower priced batteries, but in the end went for the recommended AGM battery. AGM stands for Absorbent Glass Mat, see this link https://en.wikipedia.org/wiki/VRLA_battery , very interesting. They are safer then "wet" batteries, can be positioned in whatever direction, and the plates can be flat or circular. I chose to but an Optima AGM battery, which I got from Tayna in Abergele, and the cells are circular - I posted a photo of this only a few weeks ago in the Auris section on this forum - check it out. It cost me £130 and as I live less then 40 miles from Abergele, North Wales, I went and collected. They do next day delivery for about £8. Order before mid afternoon (cant remember the cut off) and you will have it next day already charged up and ready to fit. And when I say ready to fit, that is what I mean. The original battery has a vent pipe for the fumes. This is important as the battery sits within the passenger compartment and a build of of fumes would be very bad (could cause explosion). I have heard of people fitting some AGM batteries and having to adapt the vent tube form Yasa to the "new" battery. Not with the Optima, the original vent tube just pushes in the fixture as did the Yuasa.
So I paid £130 for a Optima AGM battery, and I understand Toyota will do the Yuasa for the same price or not much more, so dont spend your £190 yet !!!!!