I think you should really speak to your son. Don't simply make a decision and assume it's good enough because a few people told you so on a quilting website. Since the FOG is an official member of the wedding party I think a decision needs to made together with the bride and groom. You might propose that you'll rent a tux , but forego a gift-- or work out some sort arrangement.
Heck, maybe the bridal party can all throw in $10 a piece to cover it. I know mine would have--gladly.