Garter & Seed Stitch Cardigan - Which Yarn?

[PBELKNAP]

I'm thinking of knitting this:

http://www.e-patternscentral.com/det...=221&criteria=

I'm at a loss to figure out what yarn might work with this. I went through Yarndex, but a lot of those look expensive. I thought maybe Lamb's Pride Bulky...The gauge for the pattern is 12 stitches to 4 inches and 22 rows to 4 inches, but the needle size is an 8...which I don't get. You'd think, for a bulky yarn at this gauge, you'd want at least a 10.

Has anyone knit this before, and if so, what yarn did you use?