Recycled Retaining Wall

So, we've lived in our house for almost 5 years now and have yet to do much of anything to the backyard. It's been a frustrating battle with Bry to get things done. I have a vision that I try to explain/show him, but he just sees cost, time, and cost involved with all of it and so we haven't done anything.
Rewind a few months to when one of my friends posted a video about a recycled water bottle schoolhouse.

After watching this video, I was motivated to try it on my backyard retaining wall, subtracting approximately $1.50 per brick in expenses to the retaining wall I've been trying to do for the past 5 years. I have a feeling it's going to take me another 5 years just to get all the bottles for the wall.

Start by drinking a crapload of 20-oz water.

Place the empties in a container that
won't blow away.

Fill with dirt from yard and place in an area that's out of the
way.

This is the wall I started when we moved in. The dirt that filled
the bottles in the previous picture is what's cleared below this
small portion of wall. Not much.

This is the length of yard that needs a wall.  o.O A Daunting Task.