For more specific info, you might look for a game composer's forum, but arcade games are likely a bit different from the console and computer varieties, which are budgeted somewhat like a film; you can figure music for up to twenty percent of the production budget, twenty-five, if you're Bernard Herrmann. (used to be less than five percent, 'til the industry as a whole started out-grossing films; in fact, ad budgets can now rival those of major motion pictures) but arcade games are a much smaller slice of the entertainment pie than they once were. There's also a manufacturing aspect to an arcade game, involving transportation, materials, labor; a substantially greater unit cost than software, which comes on a hunk of plastic that costs a dollar. With a software product, you pay voice actors, animators, artists, and musicians the twenty, twenty five percent of what's left after manufacturing and distribution are covered, and the rest is split roughly evenly between promotion and a variety of computer-related specialties I'll refer to as simply 'coding'.

(arcade games don't have anywhere near that kind of advertising budget; their target is shopping centers and entertainment districts)
You might want to try to get a sense of the scale of the project, so find out whatever you can about it; your uncle is probably your best resource, here, but don't overlook the obvious, such as googling any names you hear of that are connected to the project. Some things that'd be handy to know?
- How many units will they be building?
- Will the rollout be regional or national?
- Are the investors pioneering a new technology, 3D imaging, flatscreens?
- Have they successfully done this sort of thing before, and to what extent?
Some thoughts: You want to get your money on the front end, cuz unless lightning strikes, there will be no back end money. (in the event that it's a runaway hit, spawning sequels and a movie franchise, it might be wise to make sure you reserve all other rights when you license your tracks, if possible) To the guy that writes the checks, you're just another item on a long list of expenses, so looking at it from his angle, I think I'd be thrilled to pay $1000 per track, if I were building a thousand units; it costs out to a buck per song per unit. (looks very manageable on paper, and easily justified, particularly when expressed as a
percentage of unit cost) I also think that if they're making 10,000 to 100,000 units, the price moves toward $4k/track, particularly if I have a track record or some indie cred.

Be sure and factor in that unit cost, if you can find it; some arcade machines can run $20k-$65k and are more a ride than a game, a new pinball machine is likely in four-digit territory. (unless it licensed tracks from KISS, that'd bump it to five, heh) Try to get a sense for what they
want to pay, cuz you want them to come back for more music, yes? Others will have more to offer; I haven't done one of these kinds of deals, as yet, I jes
used to know some folks that owned an arcade, heh.
