be careful if you are on limited budget. your 100$ willl last just like anything in few clicks without any sales…
let’s do a math here – your country would be US or so , your CPC would be 3$ at least, For 100 clicks you will spend 300$ and with a typical convert rate of 2-3% on clickbank (Being a clickbank affiliate i know how it is.) you make 3 sale. That makes it 3*20 = 60$ in your commission. that makes it overall 240$ loss per 100 clicks. profitable ? Good luck
You can make more commission by promoting better priced products but that would make you CPC more and convert rate less making it almost same thing as above.
Tip : Get a review of that product on your own domain and then advertise it. The convert rate will be much much more than direct linking.
The current product I have running on adwords (From clickbank) costs 3.6$ on Avg per click with a 18% convert rate from my review page giving me 21$ per sale. Still at this much rate the margins are very low and i always wishes for some upsells. Upsells are the only thing making me keep running it with a high risk of lossing money anytime.
Do some maths and then decide before you invest your time..direct linking have a very very low convert rate. #warning