Legalities aside, I'd think it would cost a lot more to make wine from juice or kits than it does to make from grapes (paying 1 or 2 middlemen), so you may struggle to make money.
I've seen.
Say a 6 gallon kit is $100. Thats over $4/bottle.
Fresh juice near us is around $75-100 for 6 gallons, so $3-4/bottle
Grapes are roughly $40 for enough to make 6 gallons, so $1.66/bottle.
If you grow your own grapes it's even cheaper. (I get 15 gallons or so from my grapes in back yard, costing me almost zero).
Then you need to add the common costs like bottles, corks, labels, Chemicals (kits usually include this but very small cost).
Making from grapes has a higher upfront cost as you need to buy a press, crusher, destemmer, but cheaper in long run.