@Lollybags: You are sure to find a made to measure option for a suit for $900 – here a made to measure business suit, from a higher end menswear store – can be as little as $500. Perhaps they’ve come down in price, though, because the cheapest I’ve seen them is $1200, and that was a few years ago. Regardless, they are a brand where part of the price you pay is for the label, so I tend to avoid them. I will admit that some of the things they make really have fantastic style, and I have either bought, or lusted after, them. For many years I really, really wanted one of their suits, but I’ve since learned that the reason I loved them so much was that they are a really great cut on my body, so it FIT me really well.
Many men wear black suits to everything beacuse someone at a store once told them that, if they’re only going to have one suit, it should be black, and that black suits are good for everything. I was the same when I bought my first suit. A black suit isn’t wrong, but it isn’t very good style. Suits, themselves, aren’t formal dress, so black with no pattern actually doesn’t fit. A black suit is only the perfect attire for a funeral; it’s ok attire for everything else. A black suit is 100% correct for a funeral, and ok for everything else. A charcoal or navy suit is 100% correct for almost everything, and okay for a funeral.
Again, a dinner suit is NOT a business suit, and can’t be worn that way. Your FH would look ridiculous trying to wear it instead of a suit, ad disrespectful wearing it at a funeral.
At any rate, there’s no NEED for a black suit in one’s closet, but there is need for a navy blue or charcoal – unless you’re in frequent need of mourning clothes. Personally, if it’s between adding a black suit to a closet with several other suits, or adding a dinner suit to a closet with no dinner suits, I’d buy a dinner suit.
Edit: I would suggest reading the “buying” section of http://www.blacktieguide.com, and looking at the options there, and also asking around to some other places to men who’ve owned a Boss suit they’ve bought recently about the quality – maybe it has improved. But, I would be tempted to say, find a dinner suit with the details and general cut he likes, and probably for a little less than $900 (maybe like $400-600), and then spend your money at the tailor on immaculate alterations. http://www.styleforumn.net is a great community for advice on these things. Of course, like all communities, it has its share of nutbars and nitwits, so don’t take the members’ posts as Gospel. But, before buying a tux, really, really DO read http://www.blacktieguide.com