Hi I don't breed or sell slugs, but I did see some for sale online the other day, I believe on eBay. I would look into the legality of ordering from someone there, especially if importing from another country, and I've heard of a lot of scammers on there as well (though I'm not sure how - maybe misidentifying them?) so just be careful if you go that route! But I saw some of those giant banana slugs, as well as some very interesting flat slugs that I kind of wanted to hold if I'm being honest. XD
I found the listing when I decided to see if there's a market for smaller slugs - our yard is FULL of them, and I'd rather go out there and collect them one by one and even just give them to someone than use a pesticide, salt or anything cruel now that I've discovered how awesome snails are!