If it’s floating you aren’t getting all the air out of the bag. If you sous vide regularly, it may be worth investing in a vacuum sealer. If you don’t want to do that there’s all sorts of videos that show different techniques for getting the air out. Experiment and find one that works well for you.
I would first have a conversation to find out if selling is something they’d be open to. If they aren’t interested in selling, you might see if they’d be open to doing a deal where you pay them a fee for right of first refusal. That way if they ever do decide they want to sell, you will get first crack at it.