This is a tough one. The problem with local only backups is, what if there's a fire?

I use Amazon Glacier to store my pictures. It's $0.0036 / GB per month, so I pay less than $2/month for ~535 GB of storage that I'm using right now. There is also a cost for downloading, but if I need it, I'm going to be happy to pay it (and the costs aren't crazy). Uploads are free.

(The other problem with Glacier is that it's not really an end-user-friendly experience, nor is it something easily automated. I use SimpleAmazonGlacierUploader, a Java program someone wrote, to do it. You can also upload to S3 and have it archive things to Glacier automatically - I've never tried this but it should work.)

I considered getting my brother or a friend to build two storage servers (with RAID5 or something) that we'd each keep at home, and just sync to each other. Good if you have a friend or family member willing to do it (or at least host your offsite box). Down sides: Cost to build it, time to build and maintain it, cost to replace things that break, plus cost for electricity. I've been using Glacier for many years, so by now maybe I would have spent less on that theoretical backup system, but I also did not have to worry about it.