The first answer is "Probably more than you are paying for it!" However, there is such a glut of good wine on the market, and far too many grapes being produced that the cost of a good bottle of wine is relatively inexpensive. Of course, now that the Chinese are becoming significantly more prosperous in this - the "Year of the Dragon", and believe they have or are acquiring a taste for good wine, they are buying up the very top end of the market which will certainly push up prices for that segment.
The Chinese are also buying up a lot of wineries and parcels of land that produce grapes around the world and more wine will find its way to China over the next several years. This will reduce the global glut somewhat. But by looking around, you should still be able to buy very good wine for under $10 per bottle and even cheaper.
The average bottle of wine in my cellar is around $40 - $50 per bottle, but then I have some truly great wines in my cellar, and many of them have 10 - 20 years of aging built into them so I have a large stock of great wines which are drinkable today. Yet, I also have a large number of outstanding wines I paid less than $20 per bottle for. I have very few wines I paid over $100 per bottle, as I find it is just not worth it except for very special occasions to drink a bottle of wine that expensive. You just do not need to.
Blake Stevens, in his recently published book (which I have reviewed) "Still Stupid at Sixty" has a Chapter entitled "Don't Overindulge in Passions". The point of the chapter is that we can get carried away with our passions and really overspend because we want to treat ourselves to the very best. He believes that for most things that can be purchased, for the very, very best (measured as being 100% of possible capabilities and quality - assuming you can actually measure these traits at all!), you are paying 10 time more than if you accepted an alternative that was at 99% and that still costs 10 times what the alternative at 95% of capability and quality would cost. He says this applies to jewelry, stereo systems, and wine among other things. It is easy to spend $1,000 for a bottle of wine and for that price, it better not just be excellent, but it should also be rare and have collectible value. But I can find wines for $100 per bottle that almost all people would say was as good or better than the bottle that cost $1,000. And I could buy bottles of wine for $10 that many if not most people thought was as good or nearly as good as the bottle for $100 or even $1,000. I think this is true and it is why I have very few bottles anywhere close to $1,000 per bottle (Only two which were used for my wife's 40th birthday party!). Do not overspend on wine! I believe for most people, they do not need to spend over $20 per bottle and there are a number of annual reviews by wine critics that recommend the best buys you can get for under $20 per bottle. This is a very safe way to buy wine that you know will not disappoint when you open a bottle or bring one to a party.
Two years ago, we did a tasting comparing wines that were made half of the Shiraz grape and half of the Cabernet Sauvignon grape. We tasted a line-up of Penfolds Bin 389 with vintages from 1995, 1996, 1997, and 1998 and a Wolf Blass Grey Label from 1996. The Penfolds Bin 389 would have fetched $35 - $50 when they were sold and more now. The Wolf Blass Grey Label was bought for $16 per bottle (I am so glad I bought 3 dozen of those, but I only have one bottle left!). However, the group of very discerning wine palettes that evening pick the Wolf Blass as the best wine, even though it cost half or even a third of what the Penfolds Bin 389 vintages cost.
An American friend of mine who had been living in Australia for two years at the time had dinner out with my wife and me and another colleague visiting form the US. I brought two bottles - one white and one red - to the Indian BYOB restaurant we were eating at. After finishing both bottles and still having a decent amount of food to eat, my American friend who had been in Australia for two years and I went to the bottle shop next door to get another couple of bottles. I asked him if he had any favorites he wanted to drink and his response was "Steve, when I arrived in Sydney two years ago, I decided to pay about $30 per bottle and I thought the wine was really good, so then I backed off to about $25 - $28 per bottle and still thought it was really good and then backed off to about $20 per bottle and it was still really good. I am now down to about $8 per bottle and still think it is really good! Therefore, you pick something out you like!"
Like I said - and especially in Australia - you can get some really good wine for under $10 per bottle.