I'll help. I have 18 years in the biz. Start at a reputable retailer, a store that exclusively deals in aquatics is preferred. Determine the type of fish you like before selecting final tank size. You can really only go a few ways:
1. Coral reef tank with lesser agressive fish, more focus on inverts, corals and algaes);
2. Saltwater community with smaller, lesser agressive fish some and fewer inverts;
3. Larger, more agressive species (triggers, large angels, groupers) no inverts.

As for tank, no matter what the size, don't CHEAP on equipment. By quality parts and ensure you have excessive filtration and a protein skimmer.

Expenses will be dictated by size. A good quality set-up in the 50+ gallon range would push $1.5K easily.

Ease on maintenance is influenced by many variables. Namely, size of aquarium and if you have over stocked and over fed.

If you buy quality from the start, the system will last your lifetime and make for a well run, easily maintained aquarium. You'll love it. No harder to run than fresh, saltwater just has slightly more upfront costs, but well worth it.

Feel free to PM me anytime for follow-up questions.

Cheers,

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Canuck Oil