I do not know the Challenge name brand, but weight alone means little.
I just ordered new sails and went with a lighter weight HM cross stitch. You want a sail that will hold it's shape longer, not last forever, and the cross stitch achieves it. I put 4 old sails in the dump. Still "servicable" - which means they work, but you can't point as high and the rail is under all the time. Part of the question is how "well" do you want to sail ?
Half price sails - what do you think ? Material and labor costs are close to the same for all on a per yard or hourly basis. What you don't pay for, you won't get. Both North and Doyle will treat you fairly. I don't know the others. Sounds like you are in the area, so you could get a price from my loft, Harding Sails in Marion. Smaller operation run by real sailors.