Is it smart to buy this advertisement??

This kind of question is really hard to answer since buying ads depends solely on your needs, target, and budget.

I really like buysellads and use it often but dont expect the world from running a banner on one of these sites. Its a good way to get more exposure but often its more of a branding purpose then making money.

While buying an ad like this, make sure the target site is closely related to yours/your squeeze page/your niche. That you are in the same niche or sub-niche, essentially.

Read the description of the site's owner, what he says about the demographics. You can also look up the demographics on sites like Alexa or Quantcast.

Compare the demographics with what you are offering and consult your common sense. Is it a good match? If so, go for it, but don't forget to split-test while building a list. You can split-test different elements of your squeeze page, or if possible, the position of the ad.

I went to Compete.com & Alexa.com to verify their traffic stats of 45,000 monthly visits. Compete can sometimes under report traffic by 50 - 66%. Bouncing this info off of Alexa.com I could estimate that they may be close to 45K visits per month.

Now that I have verified that info I now want to estimate the CTR (Click Through Rate) & the Conversion Rate. For banner ads it is typically 0.09% (The article is a little old but is conservative - Average Banner Ad Click-Through Rate (CTR) Stabilizes at 0.09 Percent | Kikabink News - Internet Marketing News).

Conversions depending on the landing page can be anywhere from 0.5% to 2%. It can be higher but you are getting them there through a banner ad rather than value driven content marketing.

So if we run the numbers - 100,000 impressions x 0.09% = 90 click throughs. Of those 1% (conservative) will buy = that's about 1 sale. So if your product is $150 (the cost of the ad) you just broke even.

You should always evaluate and drive back to numbers that make sense and are conservative. That way you won't be disappointed.

Also, consider you will be getting branding out of this exercise and your conversion rates go way up if you give away something of value for free, build the realtionship once they are on your list and sell them something once they are deeper in your funnel.

It is related to my niche but will it bring in at least 500 subscribers if it gets 100,000 impressions?

If your purpose is to just build your list then 500/100,000 = 0.5% conversion rate from Click to sign up. It will all depend on the offer in your ad. It must be compelling, have extreme value and be free to get that high of an overall conversion.

Again the CTR for banner ads don't change much so that would still be 90 click-throughs. That would mean you have more than quadrupled the average CTR for banner ads. That's just the CTR - once they get to your page no matter how good your offer is there is still a % conversion that occurs.

I'm also planning to do this, aside from smart buy advertisement, what else I can do to have more traffic?