Technically 98 RON is equivalent to 93-94 octane. However, I believe what @Darkseid69 is saying is that the 98 RON, specifically in Australia, is actually more like 91 oct. Just like 91 octane in Arizona, California and Nevada here in the states is much worse than 91 oct in the rest of the...
Yes, please tell the middle men that overcharge to kindly F off and do it yourself. Under $1000 USD. Put an airtag in the box for peace of mind, or more anxiety from checking the location every 20 secs. ;)
I remember when Viscunti was charging $4,000+ for this.
I agree pretty much with @AJRMKV, although his DI prices listed are a bit inflated, and his PI prices are a bit understated.
However, you really need to figure out what your goals are because that is another vector in the decision making here.
Don't want to plunk down $6,000+ to build your...