Hi I want to buy a semi-managed vps 20gb space (the more the better) 500gb bandwidth 512ram guaranteed/ 1gb burst kloxo $15/month
What do you plan on using the VPS for? You may have to raise your budget a bit because most VPS providers don't want to oversell the RAM, that's something you don't want either as it would affect performance.
We recommend you xen vps where there are no way to over sell RAM. You have 8GB, all you can sell is 8GB.
Semi managed normally means basic OS management such as OS updates, server hardening and monitoring this exclude configuration of some OS related applications/services (eg MySQL, Apache, DNS) which normally covered by fully managed... but then again when you have control panel you should be able to do these on your own. If i were you get at least DirectAdmin CP than kloxo although it will be though one at your price and specs. All the best.