To the best of my knowledge, lightweight, cheap, and aluminum do not really go together, unfortunately. If you want aluminum I'd go for the DT Swiss G1800 wheels, they're not very light, like 1850g or something, but super solid and only about $350 new. If you really want lighter weight, you probably have to get carbon wheels. I know ICAN has 1200g gravel wheels for $650 but I bet you could find some slightly heavier, cheaper ones elsewhere too.