I just worked hard (and time is money!) + some money for hardware and some Press Release and ads (about $2500 I think). I've done everything myself so far.
I will add this to the post, thanks the comment
PRmac.com (you have to do it if you've got an app and it's cheap) and 3 times I used prweb.com which is much more expensive (and there is a lot of discussion to know if it is profitable but it is more professional). For the ads I went to theiphonemom.com and bestkidsapps.com. Honestly I don't know if the ROI is enough for ads on these sites - I've stopped advertising there but I looking for new place (or will come back to these places) to put ads because I have to
what do you mean exactly ? I just wanted to say that it was an investment because I did not work as a contractor or employee while creating apps. But in a sense, I could estimate the cost because for the first 8 months I was not profitable and have to use some money I've have in the bank.