Never tried strings from the web: to be honest, I've never bought
anything from the web.
Over this side of the Pond there's a firm called:
www.stringsdirect.co.uk
Their prices seem good, they've got a fast email customer service setup, a descriptive section about the strings they sell and they sell all sorts, not just strings.
I'll definitely give them a go next time I'm in the market for strings.
No doubt there are similar companies in the USA.
John