Maybe? I think it would just depend.
If I absolutely loved the toy, like it was my favorite thing on the fn planet, I'd be more likely to do it. It would also depend on exactly how expensive it was.
I wouldn't be opposed to buying even a moderately expensive vibe that I already owned in a "limited edition" color that I absolutely loved that wasn't going to be around forever.
My reasoning would be that eventually, the toy I already have WILL give out. When that happens, it may be discontinued, or the super awesome limited addition color might not be available.
Downside being that buying a toy for "safe keeping" would probably make whatever warranty was on it useless. Would a one year warranty still run out if I never opened the box?