Welcome!
Don't be stressed out - I've found that only the set-up of
SW is harder - once you decide how you want the tank, it's just as easy as freshwater. I'm sure you'll end up with a beautiful reef tank.
For filtration, the most accepted method around here is to use sand as substrate (many are fond of deep sand beds), and live rock (one to two pounds a gallon - be aware that some are denser than others - fiji is less dense, keys rock is more dense, tonga has some pretty shapes, and keys rock comes with lots of critters - it's really all about what *you* are looking for, and when in doubt, get a mix!).
You will likely want a protein skimmer. Aqua C Remoras come very highly praised around here, and I use a CPR BakPak. I believe either one is a fine choice.
For cycling, you will not need to use a fish - you can cycle with just the die-off from the live rock you get (you may want to purchase uncured live rock - you will experience more die off (fine for an uncycled tank), so it's cheaper - if you had a cycled tank, you would have to cure the live rock yourself before adding it to the display).
I know very little about reefing, my system is
FOWLR, as my future systems will likely be, but there are plenty of other members here who can help you out in that respect.
Regarding the cost of your tank, there's a thread on that which I can't seem to find. It's titled "How much to expect to pay for a reef tank" or saltwater tank or something like that. You'll know it when you see it. Seems pretty accurate.
To cut down on costs, you will likely want to purchase uncured
LR (see above), and you *may* want to consider purchasing a used tank - these things do not have great resale value. The problem with the latter is why the tank is being sold. Sometimes it has a leak you aren't told about, sometimes it was cleaned improperly, etc. Most of the tanks I have purchased pre-used have been just fine, but don't be afraid to enquire why they're selling - it's usually due to moving constraints.