Some of the top vendors that I have worked with include: Adtech, ZEDO, DART, Atlas and Mediaplex. If you cannot afford to use one of these vendors, you can ask the advertisers that you buy banner ads from if they can track view thru bookings for you. You would simply place their tracking code from their ad server on your confirmation page of your site before the campaign went live.
If you only fly from LAX, for example, then do not run banner ads to people living in NY. If your hotel is in Memphis and most of your visitors come from a five hour drive radius, then target users living in those cities or users looking to visit Memphis. Keep in mind that view-thru tracking can work for both B2C and B2B travel organizations. Perhaps the best idea is if you turn to a vacation rentals advertising specialist. So even if you sell travel technology or services in the industry, you can still run banner ads on B2B websites like Tnooz for example. You would place the tracking code on your website where a prospect would purchase or perhaps fill out a contact us form. If that user has viewed a banner ad on a B2B website, and then visited your website later on, you would know where that user came from.
I like to think of a banner ad as an outdoor billboard on the Internet. You drive by that billboard and of course cannot click it. But you do read it, remember it and take action later on. A banner ad it turns out has the same effect as it clearly influences purchases both online and even offline. One study from Comscore showed that running banner ads leads to a 274% boost in the number of searches for your brand on search engines. This concept makes sense as people are more likely to type your product into Google after they have been exposed to your brand online. Another study from Media Post showed that a banner ad impression influences 70% of all user conversions or bookings.
Even beyond bookings you also should track anyone who signs up for your loyalty program or email newsletter after they have been exposed to your banner advertising. So if you are not able to track all these bookings and traveler actions, then I highly recommend that you do not waste your money buying banner ads. You will be disappointed if you only measure success based on banner clicks so make sure you track the full extent of your banner campaign.