Is there an actual value for the buffer capacity of acetic acid?

I need to know the actual value, so that I can calculate the percent error for my lab.

Yes there is but it depends somewhat upon the pH of the buffer. Let's say the pH of your buffer is 5.0. The buffer capacity is the number of mols that may added to 1 L of a buffer solution that will not change the pH more than +/- 1.

So for a buffer with a pH of 5.0 you want to know how many mols of a strong base (for example) that can be added without changing the pH to more than 6.0. You can calculate this from the HH equation.
6.0 = 4.76 + log (b/a)
That will let you calculate the ratio of b/a.
Than knowing a you calculate b in mols/L and change that to grams NaOH. Or if you know the M of the NaOH you can calculate the volume necessary to obtain that many mols of NaOH.