I really hate to rain on anyone's parade but it has to be done from time to time.
Whilst the idea of an online shop sounds straightforward, it's only a fraction of what’s needed for a successful business. Being young and energetic helps a little, loving magic is slightly useful, and having a bit of stock will come in handy.
However what are your business skills? Your marketing and administration skills? What sort of capital can you afford to invest, tie up long term and potentially lose in this enterprise? How are you at dealing with taxation, banks, accountants (yes, you will need one) and other professional advisers? Are you prepared for what is currently a very pleasant hobby to become the bane of your life, having to work far more hours than you expect just to keep afloat until even the word ‘magic’ becomes distasteful?
How well can you deal with customers? Not the nice kind who place orders, pay up and say thank you but the ones who bitch, moan and generally make your life hell if the deck of cards they ordered at 11pm last night didn’t get pushed through their door by 8am this morning? How about the ones who lie through their teeth and swear that an item didn’t arrive, or if it did it was broken even though it’s obvious they broke it through their own stupidity? How about when you don't have an item in stock but a customer states that your website said otherwise? Check the recent threads elsewhere on TM for more depth on those and similar topics from a customer's point of view. The sad truth is that, in the eyes of most customers, you will only be as good as your last order and customer loyalty is a very rare and fragile thing these days.
OK all the above may be somewhat extreme but a lot of them have happened to me in my non-magic business and I daresay the magic suppliers who advertise, visit and post on TM can quote even worse examples from their own experience.
Yes, magic can be fun and very rewarding but a business is a business and no quarter is given, no excuses are believed, no prisoners are taken – it can be dog eat dog and you will get opposition from the existing suppliers who have been around for years and who rely on trade in magic for their livelihood.
After all that, best of luck

!