Day 1, Project 1. . . Hurdle 1, too?

I've decided to keep things simple and knit through Made in Brooklyn in order, from beginning to end. As such, I've begun with Rockaway -- a Cowichan-inspired knit. The first hurdle? To substitute or not to substitute. The materials list as written costs a hefty sum, one that I simply cannot afford. I've made my first adjustment to Jared's work by substituting a more economical yarn, Gedifra's Akona (50% wool, 30% nylon, 20% alpaca). Rockaway calls for machine steeking, which should take care of the nylon problem. But what about the issue of substituting?

Pattern: Rockaway
Cast On: January 1, 2010
Needles: US 10, 11
Yarn: Gedifra Akona
Size: Small, 39 1/4" bust (note errata for this pattern; pamphlet lists as XS)
Made for: Me