Yarn substitution

[Eloewien]

I have been wanting to knit Annie Modesitt's Corset tank top (http://www.anniemodesitt.com/patterns/#Corset) for just about forever. The problem is that there is no way I can afford the artyarns regal silk it calls for, or any other silk for that matter. MAYBE if I wait for my $200 bonus in March that i'm getting from work I might be able to afford it... but I'm thinking I'm better off with something less expensive.

I tried a cashmere/silk blend when I had money to splurge last year, but that stretched too much. Any suggestions for a yarn that has ease similar to silk but is less obscenely expensive??

Thanks!

Laura