> What would their sales be like if there was no MAME?
Actually, there's not a lot of evidence that hobbyist emulation does much to this stuff. Classics packs and the like (Nintendo's Virtual Console, Sony's PSOne Classics) have sold steadily in spite of the easy availability of emulators. Why? Because it's infinitely easier to use, and a completely different experience all around. No ROMs to find, no settings to configure, the emulator involved has been professionally QAed, you play on your big-screen home theater which probably has far superior speakers to your PC, and you sit on a nice comfy sofa instead of a hard office-style chair. Plus your 360/PS3/Wii are guaranteed to always be fast enough, and the games don't take up space on your computer.
Additionally, a lot of official classics have online capability, trophies/achievements, and remixed graphics, sound, and difficulty choices. MAME offers only online out of those things, and even that's a less polished experience compared to Xbox Live or PSN.
> I would think that there would be less sales before Mame, and that these collections > are a by product of the emulator experience.
Nope. The only thing we've observed a direct sales effect on from emulation is the price of used PCBs on eBay. Undumped games typically fetch a much higher price (sellers even often put "not in MAME" in the description), and that price typically falls immediately when Guru or Smit announces a new dump. (There are exceptions: games that are extremely rare will sometimes be worth *more* after people can see it running in the emulation and decide that they want one).