If you are short of change, use washers. In fact, different sized washers have different thicknesses. I used quite a few large (for 1/2" bolts) washers last time I needed to stretch a spring.
I've also used a brake spring tool. Its a funny style pair of pliers that grabs a brake spring, but one of the handles (roughly 3/8" diameter) has a deep groove near the end and this end is flattened somewhat. You put the groove over the post the spring connects to, and hook the spring around the round shaft. As you lever the handle stretching the spring, the hooked end of the spring slides down and over the post. I know this will probably not work on the ST (the spring needs to land on a post, or rod, not in a hole) but it might give you ideas. I remember struggling mightily to hook both ST's springs on my center stand.