I'm not totally sure but I've heard and I've read that it's possible to pay into Saudia lounges. I'm not sure how much it would be but I'm pretty sure that it would be more than 40 riyals, probably more like 100 or more. It may be possible to get in with certain credit cards or priority pass, if you have it.

One piece of good news is that the new lounge for Saudia in Terminal 2 (international departures), appears to be open:

http://www.saudiairlines.com/portal/...00d59618acRCRD

Another option is the lounge in Terminal 1, the foreign airlines terminal. It's connected airside to T2. Last year, just after this lounge had opened, I had to pay to get in. Even though I was in business my airline hadn't yet arranged for access. It was 160 riyals then. I'm not sure about now. Again, certain cards may get you in for free. It's a just ok lounge with just ok seating and not so good food.