Usage patterns
〈物〉が割安だsomething is comparatively cheap / a good value
This hotel is a better deal than other accommodations.
〈物〉を割安で買うto buy something at a bargain price
If you buy in bulk, you can get vegetables at a bargain price.
〈物〉が割安になるfor the price of something to become relatively cheap
Booking early makes the plane ticket relatively cheaper.
〈物〉は〈物〉より割安だA is cheaper in value than B
This plan is a better deal than the other plans.
