I would say it depends on whether you want a shrink copy or not, and what condition.  I know some folks prefer opened copies over shrinked.  My guess is well over $1000 for shrink copy, though I could be wrong.

i would say roughly 23 bucks... but you're lucky! today i have some "spare" money and i could offer you the charming amount of 30 bucks!

I believe every module has at least 2 different values.  One is what you would expect a module to sell for (i.e. if you saw it on eBay), and another is what someone would have to offer you to part with yours.  

Exactly! Price does not necessarily equal value.

I have Roslof's copy. It's opened and in pretty good shape (probably very fine). I don't know how much the market would value it (maybe $500), but I would probably need a premium to sell it (that's why it's not on eBay right now!).

To get someone to sell something (B3 or otherwise) when they had no intention of doing so previously, will demand a premium.. perhaps a very high one. 10% over market value, 100%, who knows. There's no hard and fast rule.

If I were you, I'd just ask myself what's the absolute maximum I'd be willing to pay for a B3, which would probably factor in the probability of finding one on eBay in the next year or so, which I could get at the market price, discounting for time. Then low ball that number as much as possible that would still get someone to sell it to me. So maybe start at market value or 5-10% above (there are probably some collectors on the margin around here). I'd then raise my number if I got no hits.

I.e. Trial and error.

If you own it, and didn't plan to sell it, then the incentive would have to be good.

Anywhere from 50% to 400%.

It really depends how badly you want to buy it, and how reluctant the seller is to part with it.

That being said.  You'll find people who wouldn't sell under any circumstances.

The Oz G- and D-series mods also have some qualities that make them a great collectible as a group:  nice artwork, great colors, and the fact that they're a series (on top of being awesomely fun adventures).

Hyping your new additions, are we?

When I first saw the Oz G mod pics, I thought 'That's how the first print should look like.' Very cool.