I had prime as a secondary member for a year (two?), and just recently got prime for myself. You can share it with 4 others which can bring the cost down.
It says in the TOS that you can invite members of the same household (at the same address), but also you can share with co-workers, so I've shared with my husband, sister, sis-in-law, and nephew. Only the primary member gets streaming and Kindle books, though.
I also ship stuff for my mom and father-in-law directly to them, so it's been pretty useful to us. I do keep a pretty close watch on prices, and will, of course, reevaluate next year.