Welcome to the forum! Excellent to hear your idea and that you've done some preliminary market research.
Which coastal town are you considering? How many potential customers will visit that area (or live in that area) each year? Is it a tourist area?
Personally, this worried me a little bit:
eclectic mix of gifts for all age groups sourced from both local artists/creators and antiques/unique items.
I think you really need to clarify your exact clients, and how you intend on servicing them, so you dont become overwhelmed with options and lose sight. I would personally find it really difficult to be a buyer for your shop, since you dont have any clear guidelines. Will you have $5 snow domes? How about a $500 antique wooden bureau? Local woolen felted mittens?
Even if you narrow it down to:
Parisian inspired items, sensuous scents and textures, with no bold colours.
Locally made items which celebrate vibrancy of colour and light
A range of pricing is good, however a clear vision will help not only the stock sourcing, but will help your ideal clients find you, and your store to create a reputation for its specific and consistent style. I LOVE stores who support independent artists and designers - does the towns nearby region have enough artists to support your store? Or are you willing to expand it to statewide? Australian wide for some special items?
Im sure you have a visual in your head about what you want to create - so I look forward to hearing more about it.