>>FW here. Salt looks nice, but the fish don't seem to have the same personalities as freshwater ones.<<
:O no way! SW fish have amazing personalities. Ive seen wrasses that come up to your face/snorkel and camera when I was on the reef. My mates reef has a Blenny that comes up and perches on his hand when he puts it in the tank. Ive seen trigger fish and lion fish that spit water at you when they want a feed. A girl from the LFS says her harlequin tusk fish has a similar personality to that of a dog.
As for maintenance... Get a big fat skimmer, rated for at least twice the volume of your tank, keeps things nice and clean. Once your system is stable, you wont have issues with water quality - I see alot of people that do water changes once a month. I personally think that the idea that all marine fish are weak is blown out of proportion. You just have to be more patient with stocking and more careful with compatability.
As for costs, i'd say the a FOWLR (fish only with live rock) would be comparatively priced to a planted tank with quality parts - eheim filters, co2 bottles, ADA soil, etc.
If you live near the beach and you have access to clean water, just get a water tank and a bilge pump and collect sea water yourself - this cuts costs even further.
I the costs of a reef tank are cosiderably higher than a fish-only.