I trashed the drive side spokes (threw a chain, previously lost the spoke guard), and I've never really loved my rear rim but I love my hub (Shimano XT). I'd like to have the wheel rebuilt at a local shop but want to stick a new rim on it. I don't like the current rim because it's heavy and has a lip on it that makes it hard to get tire beads to seat (they get hung up on the interior channel where the rim tape goes because the rims have a sort of ridge there.) Current rims are WTB Trail Laserdisk.
Priorities are reliability/durability (I just like my stuff to work) over weight. I don't need a cheap wheel but don't need the absolute best. Not knowing what the price ranges are it's hard to say what I want to spend. $100 is too high, and $20 seems too low. Maybe $50 (if that gets me something decent, not afraid to spend more for a much better rim).
Some of the mavic offerings are pretty nice. I've got a EN521 on the back, which would probably be too much for non abusive XC, but if its quality speaks for other mavic products I would say give them a look. It was quite affordable too.
I've also had pretty good experience with WTB. My stock rear wheel was some XC model that took quite a beating before needing to be replaced. I still have the front one, and it has never had to be trued after over 3,000 km. I also was having trouble seating brand new tires on the rims. What worked for me was to just always pump a little above the max psi, let it sit a little bit, and then let some air out.
Stans Flows will be strong for years to come I would just get a set and have the wheels rebuilt. Maybe you can work something out with a shop to have them rebuild at a lower cost if you buy the rims through them.