To make unloaded coins is quite straightforward, or to sell small denominations of loaded coins is fairly simple. Making 1btc coins or higher value coins (we make 10btc & 20 btc coins) is a little trickier given need to comply with various regulations (which vary depending on which country you are selling to/ where you are based).
If I were coming out with a coin I'd be pretty wary of selling loaded ones. People do seem to be weirdly accepting of total strangers creating their private keys in coin form but I would've thought it would be a tricky sell unless you've earned a good rep already.
Even if you are selling unloaded wallets you face the same issue - in theory a manufacturer of unloaded wallets could keep private keys and wait until they were loaded...
Building a reputation is very hard, especially when you advise customers (especially of larger amounts) to keep them hidden! - we stopped someone taking a picture of the first 10btc coin being sold as it is obviously much safer to not tell anyone you own one! (if bitcoin did ever get to $10,000 or $1,000,000 you could become a target for thieves)