I would shy away from that type of driving traffic to your site.
Most likely even though it suppose to be targeted prospects, it's probably an outdated list. More importantly it should be an 'opt-in' list and from the price you quoted I would say that it's not.
Too, keep in mind that on any mailing you will probably only get a 1% reply and then out of that another 1% to 1.5% sell. So you need to be very careful before you spend any money.
My advice would be to build your own mailing list. You can do this in different ways, such as maybe offering a free newsletter on the subject or product and listing it on blogs, bullenten boards, etc. Also try some banners on different websites that you can get free or cheaply..
Then just have a space on the newsletter for the reader to opt in when they sign up for the newsletter. You can build a good list in a short period of time and more importantly it will be a list of people who are actually interested in what you are trying to sell...