I know there were a bunch of questions regarding group quotes and flights, so I thought I would try to answer them all in one post
All quotes (whether group or individual) are going to vary depending on the time of year you are getting married and when you book. Sometimes there are promotions like "kids free" or "early bird pricing", etc.... And as someone else mentioned the kids still have a small fee associated with them for the cost of transfers and taxes.
If you are getting married in January, your prices are going to be higher than someone in May. The same is true with quotes, the prices will vary depending on the promotions that are running at the time you get the quote.
Travel agents can get you the same perks that the hotel offers, the nice thing about having a travel agent work with your group, is that they will organize everyone for you, answer your guests questions, and help you with contacting the wedding coordinator (well most will if they have ever worked with destination weddings)
Someone mentioned getting a quote from the hotel, but then having to find someone else to book the flights through and the prices being higher. This is because the airlines do not pay travel agents to book flights. So if someone called me and wanted me to book flights for their group, but weren't booking the resort through me, I would have to charge them a fee per ticket, in order to make anything. Honestly, booking flights can be somewhat of a nightmare because of all of the fluctuation in price, so if someone contacted me to book airfare only, I would just say no. It's too much of a headache and most people will not pay the extra fee for the help.
I think that was everything, there were too many posts related to this topic to multi-quote