Are there enough people in your area to sustain your store? You said 3 other shops closed down in the past few years right? I'm afraid it would be hard to compete price wise with petsmarts petcos for supplies. If you live in a large city and can find a small space somewhere cheap enough than give it a go, or start up an internet business and save on alot of overhead.
I am not really worried about the location of the store, those who like betta doesn't matter if they are pro, semi pro or beginners or totally new, if they know there is a betta store somewhere or close to their city, believe me they will come from all over the place.
One of my retailer that i supply live in L.A and she drive once a month to my place to select the betta she want and i dont mind she does that because she pay for them and some are not cheap.
And believe me, if i have a store, i will sell my fishes way cheaper than petco and petsmart and for choice of colors, i think i have more, dont you think ??. I sell my ct males regular color here to my neighbors and friends for only $2 and i give the female for free cause i have so many of them. Just Compare my price ct to petco and petsmart, it is more than 50% off, it is like buy 1 and get 1 free.
I said 3 closed down because they were not only selling betta, they have other things too. I remember that even i was supplying those store with my betta, customers will keep coming to see me and buying from me because my price was cheaper and i have all the betta supplies they want.
So, a betta store is coming, not sure when but i am working on it :)