As a richer player, yeah there's definitely an overabundance issue with PC occurring as others have pointed out. While I get Roodoku was added so newer players would be able to earn PC easier, newer players aren't the only ones that can access and benefit from that minigame. Sure, I can't consistently beat roodoku at all for the life of me, but there's definitely several richer players who can and will take advantage of that.

Even if Roodoku wasn't a thing though, I still think there would be an inflation issue. There just aren't enough good PC sinks currently. Not everyone want to expand their inventory space to infinity and beyond, or buy the biggest house ever. Pixpet Adventure's apparently something that should address this problem, but that (understandably) will take a while to implement.

A part of me almost wonders if the price of SPC should be increased to account for the inflation, but on the other hand, there are some who still don't use those potions anyway, and it could result in backlash rather than praise if such an idea's implemented (Especially for newer players who already can have trouble earning PC).

Like what several others have mentioned already, I think the auction system is a symptom of the issue rather than the cause of it. I'm also admittedly a person that can bid fairly high, but that's also because I don't want to drown a person in bidding notifications, and keeping up with bid wars can get tiring.

A usershop search definitely sounds good on paper, but like Hunter's already mentioned, that could potentially result in more frustration thanks to people sniping all of the good deals, especially as the amount of members on this site inevitably grows.

EDIT: I also just realized houses in a way are another method in which inflation occurs. The more pixpets you can send out, the more PC you can get overall via hoards, and that's guaranteed to occur. Having 10+ pixpets out on hoards adds up quickly even if the pixpets take a while to return.