I use digital ocean. The minimum buy in is $60/year, and it gives you 250gb of storage and 1tb of bandwidth, across as many spaces (ie buckets) as you want.

I also use this as my "share" site, and for a bunch of other uses, so my ~2gb of image hosting is just a fraction of that yearly $60.

The major catch is they don't offer dynamic image resizing. I only resize my images to a few standard sizes and just use a small script to resize + upload in one shot.