Buffers can both source and sink current ("push-pull outputs".) A transistor will only do one or the other.
Buffers also take into account the appropriate logic levels, and are thus more immune to noise. By the time you implement the equivalent features of a buffer circuit, you'll have exceeded the cost of a buffer IC.
There ARE buffers with fewer than 8 signals, that are cheaper and smaller than an AC244. Try a 74xx125