Let me sum it all up so people aren't getting confused.
Starting January 24th, and running into September, there will be 20 DLCs for Elite members. The first one is a pack of 2 maps, and the only others confirmed are one DLC in February and two in March. At some time in March, non-Elite XBox members will be able to purchase a "roundup" download that has the four Elite DLCs that came out before it. No price yet, but the price will probably be dependent on exactly what is in the DLCs it includes. And again, XBL still has one month exclusivity, so non-Elite PS3 members will be waiting until mid-to-late-April to get maps that Elite 360 members got in January. And again, we don't know the price of these roundup If they're doing one roundup DLC after every 4 Elite DLCs, that means there could be 5 of them. And if they're $15 a pop, maybe even $20, you can see that Elite paid for itself pretty quickly.
But maps are not the only things that will make up the 20 pieces of DLC for Elite members. They are definitely going to do new Spec Ops missions, and weapon packs and campaign DLC are also possible.