Saltwater equiptment doesn't have to cost hundreds. Being handy at diy or searching around ebay, fish clubs, etc can bring the cost down quite a bit. It is the time needed for researching that is the most resource consuming if you play it smart.
For example, I was recently given a second hand tank (granted it was only small, around 15-20 gal, but will make a nice nano), I picked up a fairly decent skimmer off ebay for around 60 bucks, postage included (not top of the range, but enough to do a good job) and found a few cheap powerheads that are more than enough flow for what I need at around 20 bucks (again, postage included) from ebay as well. Classifieds sections in newspapers are also great for finding a rare gem every so often (tanks and stands especially).
When setting up a marine tank don't fall into a habit of thinking that you have to get everything through an aquarium. There are people out there who are backyard tank and stand makers, have the skills and equiptment to make very good protein skimmers and all sorts of other things. There are also clubs you can join who often have members willing to help you out as well. They are often an invaluable source of info as they will be able to get you in touch with people and places with cheap equiptment, etc as well as help you with anything you are unsure about (how to rig plumbing for a sump, etc).