I'm guessing this isn't including LR, just the set up, so on that list I would put:
--55 gallon tank
--stand (if you want to go really cheap, you can diy it out of a few stacks of cinder blocks with a peice of plywood on top)
--HOB skimmer (I would go with a deltec HOB MCE300 if you can find a well priced one)
--lighting (If this is for a ceph tank, you really don't need any special lighting, you could probably get by with a $50 fixture that would allow keeping of low light corals).
With all of these things, you can get them used and take a chunk off of the price that way. If you have a local reef club, you really should join it, that would help. Also check craigslist and reefcentral (although things on there aren't always as cheap).
I'd say yes, it is possible, with everything else though (LR, salt, LS, livestock) your talking 800-1000 dollars.