I think if you are using tablespoons to the liter, you are not getting any real effect from the stop over, say, plain water. Try 1+3 or so, white vinegar to water. The main point of a stop bath is to protect the acidity of your considerably more expensive (and photographically important) fixer. If you were only doing one print in a printing session, you could dispense with it altogether.
A buffer and indicator are advantages to a Kodak, Ilford or Sprint product over plain vinegar and water; however, unless you are in a communal darkroom or print more than 60 8x10's in a printing session, you probably won't be getting much benefit from these extra "features." BTW, white vinegar in five-liter containers can be had at very little cost from Costco or other North American box-stores.
Warning: making your stop bath too strong can cause rapid outgassing in film/paper emulsions and result in pin-holes.
Have fun in that darkroom!
Ben Marks