Depends on "affordable". Current bulk prices are about $5000 per genome though the coverage can vary.

Here's the price per genome for the last decade: http://www.genome.gov/sequencingcosts/

and an explanation: http://singularityhub.com/2011/03/05/costs-of-dna-sequencing...

This blog claims 2014, although it reads as extremely optimistic, so we should probably assume 2020 to be safe.

http://blog.genomequest.com/2010/07/implications-of-exponent...