+1 librarygirl.
Unless you're keeping very finicky fish, stable levels are a lot more important than the actual values (avoiding extremes of course, like below 5 or above 10, I personally would not go much above 8 or below 6 for most fish)
In the past, I have kept cardinal tetras which ideally need soft acidic water in hard slightly alkaline water without any problems. If you are getting your fish from the LFS, chances are they use the same tap water as you so pH and alkalinity are likely to be similar anyway (unless you have really soft water).
The punch line and as a chemist I can't stress this enough:
Stay away from the pH up/down stuff! There are always some buffers in your water, soft water has less and hard water has more. The buffers, like their name suggests, "buffer" against changes in pH. If you were to use these pH up/down products you would first have to exhaust your buffer and then you'll see a pH change (how much product you use would depend on your water hard/softness but regardless once the buffer is exhausted the change would be sudden - like you could add 10 drops a bunch of times and see no change and suddenly 10 drop might cause way too big of a change). At this point your tank is really vulnerable to pH swings. I wish they wouldn't even sell these products!
That being said if you are still set on changing your pH, the buffers products you were considering would be the way to go. Have in mind that this will become yet another parameter you need to match when adding tap water during a PWC.
So tell us what your pH is and what fish you have and we're likely to tell you to leave it alone