Let's break this down. You pay him 10K. You also need to pay rent, and do upgrades to the interior. You have no idea whether the customer base will stay with you or follow him. You'll need an advertising budget. Insurance. Utilities. And you plan to spend 8-10 hours six days a week running the place. Or hire someone. How much does that all add up to? How many of your own used LPs do you need to sell to recoup even all that initial outlay? How long will that take? What will you be living on in the interim? Is this a hobby that you can afford to pour $$ into, or will it be part/whole of your livelihood? In short: "does not compute".