If you keep marine fish, you'll need to spend the next 6 months reading every book and forum plus talking to every marine fish dealer you know.
It is expensive but there are a lot of people selling stuff second hand as people either upgrade or give up.
The other thing you'll have to think about is running costs.....ie electric, salt, RO water etc. I had a gorgeous soft coral reef but had to give it up due to massive electic bills.
Have a think, do some reading then come back to us. Marines are certainly not as hard as some people make out.