Should we or shouldn't we?

We have been talking with our landscaper about some options for the backyard.  

We have been interested in putting in some type of wall into the berm to take away from some of the steepness of the hill.  We have been debating and going back and forth on whether or not we should spend the money to do this or put that money towards a deck this year.  Both are things that would be really nice to have and although a deck would be fantastic to have right away, this hill/wall is a once in a lifetime.  Well, ok, really it's not but both of us agreed if we don't do it now we would never want to tear up the yard to do it later.  If it's not done now there is a super good chance that it would never ever happen.

While we were discussing it we remembered some nearby houses in the older part of the neighborhood that had walls recently done so we decided to drive on over and ask if we could check out their yard to get an up close and personal look.

When we got home we 'drew in' the idea.  At this point we have decided to at least get it quoted.  No decisions can be officially made until we know how much this idea is going to cost us.

You can see the yellow flag in the ground, that's the height of the wall (potentially) and the 'dug in' lines are the sides of the walls that would gradually get taller.