Harvey Norman have the Forza Horizon 5: Premium Edition Electronic Voucher for Xbox/PC for $120 which is ~20% off RRP.
The premium edition includes the following:
*Welcome Pack,
*Car Pass,
*VIP Membership. and
*Two game expansions when they become available.
A good comparison of all the editions is https://www.windowscentral.com/forza-horizon-5-editions#buy
Checking the usual places this is the lowest price I could find:
Eneba.com AUD$121.44
JB Hifi $149.95
Microsoft/Xbox.com $149.95
EB Games $149.95
You could also use Game Pass (with any of the discount methods) for the base game and purchase the Forza Horizon 5 Premium Add-Ons Bundle for $62.95 if that is cheaper for you.
Note: It took about 10mins from purchase for the email to come through with the redemption code (the email referred to a link in the content of the email that didn't exist). I went to the Game page on Xbox.com clicked on the 3 dots and selected "Redeem a code", entered the code from the email then selected to install to my Xbox.
It’s probably cheaper for almost everyone. If you haven’t got Game Pass yet, you’re missing out on the best deal in gaming.