The Tripod (aka The Mount)
Tripods can be classified into 3 general types:
Regular photographic tripods
Star trackers
Computerized mounts
The type of mount you need, depends on what type of astrophotography you want to do. A regular photographic tripod will be fine for wide-field "landscape" astrophotography. This is the type of photography, where you image the entire Milky Way possibly with some interesting landscape in the foreground.
I do not recommend star trackers, because they are relatively expensive and you can get a full-size computerized mount for the same amount of money.
For deep-sky imaging (like the Messier objects), computerized mounts are best. These mounts can be very expensive, but inexpensive options are also available. The least expensive option, I am aware off currently is the iEXOS-100-2 PMC-Eight mount from Explore Scientific. As of today, it costs only $300. To get started this mount can work very well as my images on Cloudy Nights show. Of course, if money does not play a role, you may go with a better mount, such as the Starwatcher EQ6-R-Pro. This is a very good mount used by many astrophotographers, but as of today, it costs $1,900. Another option is the Celestron Advanced VX mount. The current list price is $1,200. Whatever computerized mount you chose, make sure it is an equatorial (EQ) mount. Avoid any Alt/Azimuth mounts.
Here we will focus on deep-sky imaging, so we pick an EQ computerized mount. Personally, I have two iEXOS-100 mounts and a non-name clone of an Sky-Watcher HEQ5 mount. The HEQ5 is currently on sale for $1,400. However, the mount that I use most is the iEXOS-100 because it is lightweight and sufficient for the type of imaging, I am doing.