The type of uniform changed through the progression of the war. You need to pick a time period (early war, mid or late war) you want to portray. It may be good to read the regimental history of the 8th Va. Cav. This book states that Co. K was sometimes referred to as the "Bloodtubs" due to the bright red flannel hunting shirts and caps they wore for several months in 1861. Not much else was said about subsequent uniforms. The hunting shirts were likely replaced by a depot issued uniform which was the norm for the rest of the war.

Here is a link on Richmond Depot jackets http://www.military-historians.org/company/journal/confederate/confederate-2.htm

It is likely that some of these type jackets may have been worn by the 8th.

Next thing to decide is how much money you want to spend. A good shell jacket and trousers made by period methods with period type material and an authentic pattern will run you around 400 to 500 dollars. Here is a link to a one of a few good vendors. http://www.kabar44.com/index.php

What most SCV members buy (who do not reenact) will run about 300. Qualitity varies with the particular supplier but I would buy the authentic uniform if your pocket book can stand it.

Good Luck