Thanks for that link. Didn't know about Scirra's store.
Are you talking about AudioJungle, exceeding the 10.000 'copies'? As far as I could make out of their terms is that such applies to games that are being downloaded, like from Steam for example. I could be wrong though, gonna email them to be sure. AudioJungle sure has top notch work and the pricing is low compared to other (crappier) sites.
In any case, breaking 10.000 plays/downloads of your game appears to be tough, judging from what people on the forum say, so if you do get it done could one consider a game to be succesful? If so, then paying an extra (double price) license isn't much I guess, considering your game plays will soar anyway. But that might be perhaps a bit too much on the optmistic side.
I think we don't have much choice - I guess we just need to work hard on our games, and make sure their worth playing, hopefully covering audio costs. Honestly I don't think anything like $5 soundtracks exists that also have a full commercial license. Would you? Create one-time tracks for $5? Take into account that the maker put his life's hours in, maybe even bought special equipment, and share revenue with the channels that distribute their tracks. When you start to take that into account then some sites offer seriously good tracks at a bargain.
Making games is basically a business model like any other. Maximize profit and minimize effort. Not saying we should make crappy games, but rather learn to work efficiently and earn enough to make profit so that audio won't be an obstacle anymore, since we can cover the costs with revenue.
I'm thinking for my games, is to start simple, not try to get everything perfect where it's not possible. If you go to AudioJungle you can see how many times a track has been downloaded. Choose the one's with a lower price, that still have low downloads. What are the odds that if a track has been downloaded three times that it will be used in a game, and if so, a game similar to yours, plus, would that person even remember that soundtrack? Maybe he played that game a half a year ago never to remember it again. Heck, who says the track has even been put to use and wasn't an impulsive buy?