I feel it depends on your market, your name and where you’re going to be listed with your competition. For me, yellow pages work good. I don’t spend much, but I have a really cool name and always listed one of the first three. I think yellow pages have 90% to do with the name of your business. If it starts with “A” or “B” the $40 a month may be a good investment.
My one liner easily pays for itself every year. But again my listing is usually first or second.