If I payed for advertising for an arcade or a proxy for one week, do you think that I will get any constant visitors coming back every day? Do you think that many will tell their friends about it?
I've said it before and I'll say it again. If you cannot advertise a website than you might as well quit as a webmaster. Advertising for a week will not bring you stable traffic. Advertising for a couple of months will bring you to the point of stable traffic. You can't stop advertising until you've reached the point where visitors link your site by themselves and that takes about 1200 unique visitors per day, which it months and months of promoting, link building, and SEO. Of course it depends on what the advertising is that your wanting to purchase.
Well the only person that would know this is yourself. Look at your site and tell yourself that if it were not your site and someone elses, then would you come back to it after the first time. Tell your friends about your site once and make sure they go on it once and then don't mention nothing about it and see if they end up going on it time and time again. If you site is not that good or sticky then it will be harder to attract visitors that will return.