Simple Bundles & Kits , 246 reviews

The app is easy to use and the customer service response is very prompt. The low rating is only to warn businesses that use the profit margin and cost of goods sold reports. Every time a bundle is sold, both the cost of the bundle and the cost of the items are reported for cost of good sold and profit margin. Thus, duplicating the numbers and skewing the reports. If you don't use these reports at all, this is an easy and simple app with good customer service.

This app was not for us. All we needed was a simple way to sync the components/products associated with bundles we were already selling on our store. But there were far too many caveats for us to move forward. What's not obvious from the app description:
Their default method breaks out the individual products in to separate line items on the order and discounts them 100% (screwing up your inventory reporting), but also adds the bundled SKU as its own line item (inflating your units sold). Their alternative method still breaks out the individual products but doesn't add the bundled SKU. But this effects your ability to discount properly and leave you with no way of knowing how many bundles were sold.