The K31 is really one of the best surplus rifles and any serious collector should have one. Unfortunately it leads to the "swiss flu" and they tend to multiply. I have about 9 K31's as well as the older long rifles and the K11.
A side note, I will be selling off about 4-5 of the K31's within the next 30 days here in Sacramento on Calguns. Im thinning my collection down and I've been selling off the Mosins first. They will be FTF cash and carry, so if you don't get one yet, watch the Marketplace here for them.