Margins can vary by manufacturer depending on whether they are first (eg. Samsung TV), second (eg. Toshiba TV), or third tier (eg. RCA TV).

In your negotiations with the manufacturer, I recommend that you discuss price protection to ensure that your margin rates remain neutral as the product becomes obsolete. Alternatively though, you may be able to negotiate lower costs if you choose not to be protected; however, you would want a robust exit strategy to ensure your margins are protected should your sales not materialize.