FWIW.... my DS decided that he and his new girlfriend (from another town) wanted to go to both proms (his and hers). I decided to search for a dark suit for him figuring since it is his junior year, he would get at least two years out of it (and he has pretty much stopped growing anyhow). I figured I'd start low (with the thrift stores) and work my way up.
First day out I got lucky and found an actual tuxedo, but the jacket sleeves were just way too short (he has long monkey arms!), but I didn't give up and I found (later that week) a full men's suit, black, very current style (yes, men's suit styles change and can look very dated). Took it home and it fit DS pretty well (sleeves were plenty long enough, shoulders fit well, chest/ab a little loose, but we can deal with that for $25!!). Had it dry cleaned (that was almost as expensive as the suit itself) and it looked wonderful!
I bought him a brand new crisp white shirt and a selection of ties [black solids and patterns, both regular and bow ties], (his girlfriend's dress was black so they wanted a full black and white look) and pocket squares (those stupid things were really expensive!)....the ones he didn't want will get returned.... and he looked SUPER dashing! Fortunately he already owned good quality black dress shoes and a black belt.
When all is said and done, including the expensive pocket square and the dry cleaning I will have spent under $100 to fully clothe DS for both proms! And he still has the suit/shirt to use next year!
Considering it could have cost me $100 per prom to rent a tux, I figure I am well ahead of the game!..........P