I also don't know, but I'd second the curiosity and appreciation. I want to pick these originals up for my girlfriend at some point and have no idea re: pricing.
I collect PC games, but I can tell you that we are far and few. I usually pay $5 or less for my retro PC games (Big Box or Not). To the right collector (if you can find them), they might fork over more money; however, the rest of us stick to the $5 or below rule.
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$100-$200 it looks like so your $200 listing with a best offer option is probably a good start.