On the off chance you're not aware of it, there are lots of wine drinkers blogging about wine (see Wine Blog Watch or the right column at Fermentations). Some wine bloggers place "Ads by Google" on their pages to help defray costs (see the bottom of Dr. Vino or the right column of Ultimate California Wine Blog for examples of "Ads by Google" on web logs). These advertisements are part of the delivery end of Google's AdWords program.
When you search on Google, targeted ads appear to the right of your search results, based on your search words. Google offers this same feature to Web site owners though their AdSense program. Based on the content of a Web page, Google decides what ads are relevant and displays those "Ads by Google" alongside the site owner's content. In the case of the examples above, "wine" is a frequently-occurring word on these blog pages, so Google chooses wine-related advertisements to display. Web site owners displaying these ads get part of what Google is paid by the advertiser.
Advertisers only pay when someone clicks on their ad (hence the name, pay-per-click advertising). Since there are generally several advertisers bidding on the same key word, position and frequency of the ad is determined (in part) by what the advertiser is willing to pay for a click.
The problem with Google AdWords (from the perspective of a winery) is that a phrase like pinot noir is going to be relatively expensive to use (Google estimates this phrase would be clicked on 60 times a day at $0.75 a click, meaning you could spend up to $45 a day). The phrase Russian River pinot noir would only be clicked on once every two days, and it would probably cost you $1.12 for that one click. It's more expensive on a per-click basis, but it's also more targeted, so your overall cost is lower. (I'm glossing over some details - for instance, you can set a daily budget - but the basic idea is that advertisers bid for ad placement).
But there may be an even smarter, more effective approach.
Someone who blogs about wine might be interested in your sponsorship or advertising. It can be as simple as a text link or box that a blogger places in their sidebar, and offers highly-targeted access to potential customers. How much does it cost? On a non-wine site, I have an advertiser paying $100 every three months to place a Google-style text advertisement on a single, relevant-to-his-potential-customers page, which is much better than what Google would pay for the same space (and better for the advertiser, relative to what he might pay for a strong keyword through AdWords). It's not clear if that $100 is a bargain or a rip-off, but both sides seem to be happy with it. In other words, pricing is pretty negotiable.
So: consider a low-cost experiment in advertising on a wine blog. You might even ask your (best) customers where they go online with regard to wine research, and advertise there. For example, if I were a New York winery, I'd be asking Lenn if he'd be interested in my ads.
By the way, you shouldn't even think about paying to drive traffic to your Web site until you are sure that you are able to convert that traffic into desired actions. How can you be sure? Make sure that the "visitor effectiveness" of your Web site is above average (so you don't pay for visitors who get frustrated and immediately hit the Back button), and understand how to analyze the actions of Web traffic you're already getting.
(PS - This post is not a solicitation for ads for *this* blog. Wrong audience)