I would agree that the seller is probably on vacation. However, with all due respect, I think your prematurely worried. You sent your payment on 6/25 so it was likely received by Thursday 6/27. Some sellers only ship once or twice a week. If the item was sent UPS ground, it could take a week to get there. They may have shipped the item but are bad about responding to email.
Ok then how long should I wait before I start to worry about being ripped off?