Michael had another purpose at the trade center.
It was related to his evolution points. Michael placed the highest priority on anything that could help him with them.
He didn't believe there were only a few limited ways to increase his evolution points. There had to be other methods beyond simply waiting for them to refresh daily or absorbing spirit crystals.
Michael's theory about his evolution points was that they were generated from the overflow of soul energy absorbed by his talent from him and his undead. This gave him a potential direction to explore.
If he could find items that could recover or enhance soul energy, would his evolution points also increase?
Whatever the case, it had to be more cost-effective than relying on spirit crystals. Not only did it need to be cheaper, but it also had to be efficient enough to make the investment worthwhile.