Hello- we're going to have our groomsmen wear khakis and blue blazers in our wedding... but how do we go about that? do we pick out a pair of khakis and a blazer from Macy's or J Crew or whatever and tell them to buy it or is there a place that rents that stuff like Mens Warehouse? Want them all to be in the same shades of khaki and blue, you know?

Hi, sub, I'd pick out a universally flattering cut of pant and have them purchase them.  They won't be super expensive and just about every guy can wear pants like that, again.  

Surburb, I congratulate you on being so practical. A blazer and khaki pants can be worn for a long time to come.
I would pick out a blazer and a pair of khakies, and have your groomsmen just purchase those. Lots more of a value, than renting a tux. You may even go to one of the discount stores, like Syms, and find something you like. Then have them all purchase from there.
I don't believe the groomsmen would be upset purchasng something, they would be able to wear later on. Bridesmaids usually don't have that option.