Fast Wheels has a few different flow-formed wheels that fit - FC04, FC08, FC09 and FC12. I'm running FC04's in 17x8" ET35, and they weigh 17 pounds per wheel (as per their specs on the website, and personally verified on my scale). I've run them on both my BRZ and my previous car, and they have been very durable despite the low weight. They're also fairly inexpensive - a set of my wheels is less than $1,000 Canadian, which is about $750 US.
Here's a link to all their flow-formed wheels in 5x100 bolt pattern (you can search by car as well, but there are certain fitments that will work on our cars with coilovers that are excluded from those results, E.G. 18x9" ET40):
https://fastco.ca/Fast-Wheels/Alloy-...wheelPcd=5x100
The website has specs (weight, etc.) for all of the options.