The room was clean, and bare but for a few posters of semi-nude women advertising biking equipment, a big piece of butcher paper tacked to the wall with comments by previous travellers, and a low table with overflowing ashtrays and a few random books, mostly ancient picture books of Hokkaido and notebooks with more comments by riders. The guys lounged around the room, smoking and poring over maps as they politely sussed out the leader of the pack in terms of baddest bike, and who'd had the hairiest, most exhaustingly windy or cold day.
I asked about other rider houses and the guys all pulled out cheap little xeroxed booklets and random scraps of paper full of information, from which I got a few more numbers for the next days' rides, and a music-to-my-ears review of prices. Apparently, Rider House Friend was on the high end of the scale. The average price was from 300 to 400 ¥, and one legendary place, in Hamatonbetsu, was free, if you ate at the owners' near-by restaurant. (A few days later, I stayed there, sure enough, for free, and paid 800 ¥ there for a plentiful set meal of chicken karage, rice, miso, tea, and tsukemono.)
The guys also told me about some other cheap/free accomodations which were like rider houses, but which weren't exactly rider houses. It seemed that most folks using two-wheeled transport stayed in either rider houses or these non-rider house cheapie places, when they weren't camping. I stuck to rider houses, and never stayed in one of those "other" places myself, much less figured out what they were exactly.
I did try once to track down a lead from a xerox book on a reportedly free "other" place called Jagaimo in Naroya. Arriving at nightfall after a cold 90k ride, I circled around the area where I'd been told the house was, finally asking some local boys, who told me it had closed, and who showed me the empty spot where it had been when I didn't want to believe them. Not to say those non-rider house cheap places don't exist. I was unlucky, but I reckon they do exist, as part of Hokkaido's supply of cheap housing to accomodate the demands of the flood of low-budget summer travellers. That night in Naroya, where I ended up blowing 4000 ¥ on a business hotel, confirmed what I had begun to suspect was the best way to find the cheap places; ie, talking to riders who had been where I was going.