It may violate the vendor's card agreement but I've found it to be common in business to business transactions.

The question then becomes is it worthwhile. 100,000 points for around $2000. If you are an SE and can actually access the D seats you want this is a good deal. For the rest of us ("the worthless 99%") it's a lot more questionable. Will be interesting to see how the value looks with the new redemption program (when it finally does get launched later this year).