When folks get started in witchcraft the easiest path (especially for those without a coven to ask questions of) is to read books. The next thing folks do is to try and duplicate exactly what their new book suggests. (Hence that silver bell and drinking horn I have but have never used magically.)My suggestion is to not get too hung up on altar necessities and details. If you'd like to have a boline, by all means get one. My suggestion is to purchase the best (sharp) new small knife you can and consecrate it to its task, using it only for that purpose. If you like, you may decorate the handle in some way [ e.g. paint your sigil or magical name on the handle, etc] and then *use* it in ritual. That will tell it what it is and ensoul it's double on the Astral with your purpose.
It seems to me that a small, straight knife is easier to use when inscribing a candle than a half-moon-shaped doodah star-sprinkled one, but your mileage may vary and it takes all kinds, etc. :-)