If you have any experience with fw tanks, and were successful in keeping them (particularly species oriented set-ups), I would go straight to reef (I did), unless there are non-reef safe fish that you'd like to keep.
To me, that is the real question -- what kind of fish do you want to keep? That should determine whether you want to go reef or not.
Extra time for a reef is a few minutes every day or every other day -- about 10 for me. Testing for a reef tank once it's stablilized is weekly at most, barring some specific reason to do so more regularly.
If money is a limiting factor, FO might be a better option since you wouldn't need as good of lighting, but the bulk of the other expenses related to upkeep aren't greatly different for FO or reef, IMO. If you're interested in growing coralline algae on any of the live rock in the tank, you'd still be dosing calcium and alkalinity buffer, just not as often in a FO tank. But, you'd still be doing it and would probably still buy the same size container of the supplement. It would just last you awhile longer.
You would save money by not buying corals, but even that can be done inexpensively. Most of the corals I started out with I got for free or paid $5 a piece for as frags (mainly soft corals). They've since grown (over 4 - 5 months) and are as large or larger than anything you'd find for sale at a LFS.
Essentially, cost is what you make of it. If you decide to buy everything new, it will cost you a lot regardless if you go FO or reef. There's always people around that are tearing down a tank, selling equipment, lighting, live sand, live rock, corals, fish, hermits, snails, etc. for much less than new. I'd check with a local reef club (if there's one in your area), the newspaper, craigslist, eBay, and for sale ads on the various sw boards to see what you can get in good used condition regardless of whether you go FO or reef. We saved a ton of money versus buying new when we got our set-up used. Besides, I've run into many people that if you're buying a couple things from them at the same time (especially locally), they'll tend to be generous and toss in something extra just because you're taking the stuff off their hands.
Either way, good luck and enjoy!
