$1.50/lb is more than fair and I would not expect them to ship for free.
If they had the 160# set with (2) 45#, (2) 25# and (2) 10# that is part of the 3 ships free deal and I would happily add a collar and t-shirt to get that shipping. Yes, it works out to $1.84/lb, but much better than $2.33/lb for the 25# pair.
For comparison, I could get a 25# pair of Rep Fitness Competition Bumpers for $125 and pick them up locally (eventually).
Rogue also has the 5.11 Tactical Vest on sale for $159.99 and ready to ship. Add a patch for $5 and weight plates for $60.01 if you want to have a 20# vest in time for Murph. $225 + shipping.