MODIS Data is distributed free of charge through the Level 1 and Atmosphere Archive and Distribution System (LAADS). By utilizing the Search & Order Tool on the LAADS web site, one can search and subset data by collection, date & time, geographic area, science products, and selected metadata.

  Search & Order MODIS Data (LAADS web site)

It should be noted that LAADS web site searches (link above) are limited to 2000 files; so you may need to limit the time period or spatial coordinates to complete a search successfully. If you don't want to limit either field, you can go directly to the LAADS FTP site to download data (see links below). You will need to scroll down a bit in the FTP page to find the directories that start with "MOD" (for MODIS Terra HDF data) or "MYD" (for MODIS Aqua HDF data). The FTP directories that start with "MOB" or "MYB" contain Terra or Aqua browse images.

  FTP Download Collection 006 MODIS Data (LAADS ftp site)
  FTP Download Collection 051 MODIS Data (LAADS ftp site)