Home office deduction - is it worth it?

I have been self-employed part-time and have already been able to claim the percentage of use of my phone and internet bills, in addition to mileage.  I have converted my work area into a home office, but I'm wondering if it's even worth it.  I can't use my computer at all now for anything personal and am not sure if I would be able to deduct much in addition to justify keeping it as a home office.  It's only about 30 square feet.  How much does this usually add up to on average in savings?