I am in agreement here. I was at Winona for three years from '94-'97 and never paid anything, as I did not have anything to give. I often had the same feeling, "If I get booted out, how will the benefactors feel?" It could be that some of the parishioners from my home church donated anonymously without my knowledge. I might just write a check to the SSPX seminary so as to placate my conscience. After all, I am grateful for the education that I received during those years.
No need to write them a check. They accepted you under those terms, and ... the only reason they asked for SOMEthing was really to weed out potential freeloaders who didn't go there for the right reasons. SSPX chapels all have some of their collection money skimmed in order to support the seminary, and the amount that individual seminarians pay in tuition is really just a drop in the bucket, and, as I said, mostly to keep out those who might not be serious. Whatever education you received was meant for the good of the Church primarily, and it's not like you can do anything with your STAS "degree".