Most shops that have a Glock armorer on staff should have something to help you out. I walked right into Highsmith in Greenfield and bought a Zevtech 3.5lb Connector for $19.99. Probably overpaid a little bit, but no shipping charge or waiting. I'm sure someone closer to you has some. Just have to call around.
I agree that you should call around. I bought my Ghost 3.5lb connector for about $13 at USDS a couple weeks ago, but a few times when I'd gone in prior to that they were sold out. Calling to verify and have someone hold it for you may be best if you want it right away.