Since for the op the price is the major issue, I suggest to go with Gsa. Why do I mean this?
You get far more options with gsa than scrapebox.
Gsa does everything better (dont shoot me for this, this is just my experience). It can post to hundreds of platforms, and in those are included all the blog platforms that scrapebox can post. It also can scrape target for your posting.
Also if you find Gsa internal scraper slow you can use a free alternative to scrapebox in the form of GScraper. It is limited to 100 000 results and burn trough proxies but its free.
But as satyr85 said with Gsa you have some other expenses in which you SHOULD invest eventually. I say again eventually. All of those thing make you life easier but there are alternatives to them.
You will need to buy:
1. Captcha breaker or Sniper: 137$ or 100$ respectively. This should be your first investment after you buy GSA, but you have an alternative that is free but time consuming. You can solve captcha yourself by using "Finally ask user if everything fail" or not bother with platforms that have captcha.
2.Private proxy. 10 private proxy or 20 semi private cost 20$ dollars a month. Free alternative is to use public proxy that can be found all over the web or with gsa proxy grabber that has hundreds of proxy sources implemented.
3. Vps. 40$ dollars a month. Free alternative is to just use you home computer. I have a 5Mbits internet connection and can use 200 treads. This slows my web surfing but it doesnt lowers my success rates with posting. You wont be sending 100 000 links a day so you really dont need this.
With this set up you dont need anything else but you can spend more to get higher success rates if you implement the following:
4. Spamvilla. It enables solving Recaptcha which is now on 50 % all site you will try to post. 30$ a month
5. Ser engines which enables you to create web 2.0 and social bookmarks. 15$ a month
After all of this additional money you might be thinking that the scrapebox is the way to go, you would be wrong.
The truth is that for running Scrapebox you will also need almost all of the stuff I mentioned above.
You need captcha breaking when you start commenting, you need proxys when scraping, not the mention when posting comments, vps could come in handy. It is a great software, that is true but at this moment its not for you.
Finnally, my suggestion is to buy stuff in this order:
1. GSA
2.Captcha breaker
3.SEmi dedicated proxy. More bang for you buck and work just as good.
4. Scrapebox
5. Spamvilla
6. Vps
7.Some content generation software lice WAC or similar (not expert here, i spin myself with spin chimp )
My last note is that you dont buy everything at once, but when you earn enough buy next, earn enough, buy next, etc.
This is what i did.
Good luck.