I only play single-player games as well. But I also do HBO GO which is more than worth it (our HBO/Showtime/Cinemax is free so we're not double paying...) along with Amazon Instant Video and Netflix. Plus, Live is easily earned via Bing Rewards and year cards can be purchased for $35 or less on Ebay...
I used to do Netflix as well but with Live that's like $15/mo out of my bank account.
My point is that I shouldn't have to pay for what the PSN (and soon Nintendo Network) offer for free. It's a shame too because I've really had a hankering for Mass Effect 3 multiplayer but I don't have the money for Live.