Yahoo is effectively doubling the price of an important segment of its digital music subscription service, having launched it six months ago at a price seriously undercutting its music rivals, writes CNET. In an email message to subscribers late Thursday night last week, Yahoo said its portable subscription service (which allows listeners to download an unlimited amount of music and transfer it to portable devices) price would nearly double - from $6.99 to $12 per month as of November 1. Rivals Napster and RealNetworks charge $15 a month.