If you want to save money though, you could use 2h quicken and a concentration pot (awakening if u want to spend a little more ;p) and just go around training like said earilier (something like an elemental sword would help immensely if you can find a whitesmith to make one for you)
if you are going to use SP, might as well go all out on it, or use the minimum. Bowling bash does indeed use more SP but it also keeps you flexible in that you can use both the highest sp way of training, or the lowest sp way of training without introducing a spear, in which you NEED to use skill to make the spear even remotely useful.
of course, this is being tight on money. again i suggest that you find yourself a better character to make money with and then fund your knight that way--there is no getting around how tedious it is to train an unfunded knight
