I don't think you are going to find guaranteed ram of 512MB for $30/month. I would suggest increasing your price range a bit and/or going with lower guaranteed ram and the burst ram at a higher amount.
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I totally agree, you shouldn't host a gameserver on a VPS, it simply won't work out. Get a low end dedi instead. We've been testing intel core 2 duo's quite a bit and for gameservers they are absolutely great.
The reason gameservers don't do well on VPS's is that gameservers mainly require a lot of CPU (e.g. all the CPU that a server offers).
If you're going to want your own private environment for a gameserver, you'll be looking at more than $30/mo, unless if you can find some bargain dedicated server deal somewhere at that price. If you are looking for just 1 gameserver (daemon) then why not just get one from a gameserver provider? They'll use the right equipment and even though you share the same physical machine with a few others, it'll work the way you want to and you should be able to get one under $30/mo.
I definetely do not think you will find a 512MB RAM VPS for only $30/month. Please understand that usually to add 512MB RAM to a server costs around US$20/month. Also, to run a gameserver, you will have to check on the CPU. A css server is recommended to use at least 500mhz of CPU. Try to expand your budget and look for VPS providers at the advertising forum, there you will be able to find many.