Before I give you the quote on this, let me talk through a few caveats/details for this potential feature...
1. We would place some kind of limit on the maximum number of events to display, primarily because if there are too many items, the email will be too long/large and may be rejected by certain email services. We would likely limit it to no more than 100 events per email. And note that there would be no way to see the "complete" list, if it did not represent all events.
2. Note that each group would have its own digest. In other words, the main site list of events, would not include events at the group level... users would have to subscribed to each group they were interested in to be notified by digest about the events per group.
3. Because of the limitations of point #1, it makes sense to only support daily and weekly digests, since it is more likely that a monthly digest may include more than 100 events. Thus, in our implementation, we would only support daily and weekly digest options (not monthly). If this is important to you, though, we could implement that part as a customization (additional fee).
4. As stated above, the digests could list all new events created during each digest period (and would not be a list of upcoming events).
The cost to implement this as a feature expedite would be US$2,600. And we would require 100 days to implement, from the date that you sign the work order.
If you have questions or want us to draw up the work order, please let us know!