My photography business uses teliax (www.teliax.com) to provide voicemail, with an 888# to boot. They have lots of plans, but you can do a prepaid plan that's $5/mo for the phone number (they do have the 415 area code, but they also have toll free numbers at the same price), it'll be $0.02/minute, and they can be set up to e-mail the voicemail to you as a wav file. So if someone leaves you a 3 minute voicemail, it'll be $0.06.