Understand what you mean about having to buy mill-run lengths. Same thing here. I can get them to run off pieces cut to length for my application, but it costs considerably more than my few minutes to stack the material in the saw and cut them to length. Unless we are talking something like 5000-piece quantities. Then it makes sense to consider pre-cut stock. I just ordered 5 each 12-foot sticks of 6061-T6 in 3-inch by 5-inch rectangular bar - they wanted $2.98 a cut to cut it into 9-1/4 inch long brick. Needless to say - I got sticks (of course they weight a bloody ton .....).
I have one of the Roll-In saws - it is a vertical bandsaw that "rolls" down a slight incline to saw through material on the table. It has been an excellent performer so far. Maybe someday I will get an automatic saw (not anytime soon though).