The Topas is a great case but perhaps far above your ideal price. However, the shiny Alu case is anything but stealth. In fact, it screams for attention.
Even if you paint it, it's bound to scratch off and reveal the shine underneath.
The "old" Samsonite Silhouette 12 hard-side spinner used latches and not those cheap polyurethane case with zippers that it's now become. If you can find one, that may be your best bet.
As for durability, it's almost bulletproof. I bought one of the original hard-sided spinners back in 04/05, brought it through hell and back, and only through the
very diligent inspection of a Japanese baggage boy did I find a tiny start of a crack at the bottom of the case. If he didn't find it, I'd probably still not know about it.
Just did a quick search. If you can't find the old Silhouette 12 models anymore, it looks like the Cruiseair Elite is the successor, although it uses a key lock rather than a combo lock. RevJim is right in that virtually all of them will open in "half". That's one fact that you'll have to accept.