Proxies grow very quickly with very little promotion. Your best bet is to submit it to topsites, proxy lists, and other related sites. If you have money to spend, I would spend it buying links on high traffic proxy sites, and proxy newsletters, as those would send visitors to your site who would not otherwise have heard about it.
You have to decide. The question could have been - is it wise to promote a web site .. ? .. it actually depends upon you
I find most proxy sites don't last very long. Once they get banned in certain countries, the traffic drops considerably. Besides, there are so many free venues that you could use to promote your site. ie. topsites. good luck anyhow
That is why I suggested buying links on high proxies, and email newsletters. The contracts are usually one time or small length, and after you receive all the traffic and the proxy gets blocked, you would not have wasted any money.
The best money I have ever spent on a proxy is getting my proxy sent in a newletter to a large opt-in list. Worth every penny I spent.