Well, if it costs something it's an expenditure of money. Some setups cost more than others. It's all relative but gear accumulates over time ;-) I'm 50 now, the stuff creeps into my bins, at my age I don't know what to do with it.

Suitability - It all depends on where you are going and for how long. If I go for weekend or long weekend then I usually know where I'm going and therefore I could choose the right sleep system (tent or hammock or tarp or bivy). If I was going on multi month trip then I would probably take my hammock setup and add a cuben fiber tarp like Hyperlite Mountain Gear Mid and an inflatable mattress. I would not think the extra weight of the tarp and the mattress would be a showstopper. Besides, sometimes a hammock is also nice for a siesta or a brief nap to escape the midday winds or a sudden downpour.