PSUs are alarmingly expensive; this 13.8V 32A unit was around $200. The adventurous can build one out of a $20 PC power supply (like here:http://www.transmission1.co.uk/forum/viewtopic.php?f=34&t=17983).
Antenna tuner allows my fixed-length antenna to resonate on all bands 40m-10m.
I use the microphone least of all.
I'm running Ubuntu on a 7 year old Thinkpad R51, which is adequate.