I agree the pricing is expensive.  However, "here" Roundup kills more than just grasses.   I suspect that is also true for the OP.  So, the OP may see benefit where you don't.  

We deal with common chickweed in the spring in alfalfa (and small grain fields).   And I am starting to see ALS resistance in the common chickweed. So, that starts to limit what works on killing common chickweed.  Using Roundup on the common chickweed can be another tool in the toolbox.  Not saying there aren't other options.  Just that using Roundup can be one of those tools..... and you need to have RR alfalfa to use that tool.  Just saying.