Knitting Bug?

At the weekend I bought some funky wool, using a voucher I had obtained in the local free paper. This is so I could knit a scarf (as my knitting skills are limited, and she is a owner of many scarves for playground duty) for my sister’s Xmas pressie, so plenty of time ... except I’ve got quite a knitting bug now and used up half the wool I bought, and I can see more scarves being produced for xmas pressies ... I’ve got to go back as the amount of wool I thought would produce a decent length scarf won’t, so more wool purchases to join it?