I'm amazed this thread is still running... and there are literally dozens of threads just like this one in the past.
It's a hobby. You _CAN_ go cheap, if you want to...
A 20 second search turns up a craigslist 65g tank and stand for $150.
A small used tank to use as a sump, borrow a hole saw, a few bucks worth of PVC, and a $50 return pump... you've got a running system.
A used T5 or a pair of ebay Chinese black box LED's, it's lit.
Salt, hydrometer, a cheap RO/DI system, dry rock, a jabao wavemaker...
Freebee mushrooms, polyps, xenia, monti cap frags from area hobbysts willing to help a guy get started...
You're in for what, $500? And.. you've got an excellent chance of success... as good as people who started with 10x your initial investment.
Expensive? Ask a serious golfer how much he spends annually on his hobby. Or a competitive shooter. Fisherman, hunter, boater... You get my point.
It's a hobby. The definition of 'hobby' is 'something that you spend your free time and money doing'.
You want to get involved in shooting sports? You can pick up a used pistol for $350, couple boxes of ammo, and a holster, and start competing in IDPA events immediately. Or... you can spend twenty grand building a custom long distance precision rifle, tools for loading custom ammunition, a high end scope... It's your choice. Either is a valid entry into shooting sports.
Back in the 80's, when I started with marine aquariums, I didn't have any money. A small tank, CF light strip, a box of IO, tap water and Start Right... I was successfully keeping many fish, inverts, and even several varieties of corals. Such low budget aquariums STILL WORK!
Today? Yeah, I've got some fairly serious money in my system. All kinds of high tech toys and gizmos. I'm not neglecting my kids or spending my rent money... it's mine to do as I wish.