You can normally SPI for under-book value. Thats why I have so many in my personal account. 3-4 years back, they were trading at 80-90% book-value and I shilled it in posts for a few months and nobody was buying them so I bought them all myself, haha. I'll pay 80 cent for a $1 worth of investments any day of the week.
SPI is only small and not well known within the larger HIVE community, i guess this is why the always trade undervalue. (even when we offer a 95% buyback)
Keep stacking them and soon you'll have a big pile