if you want an OS installed, it'll take up most of your space - you may want to increase that by about 5x - you can be sure that you don't buy oversold space with vps so you shouldn't be worried
I would recommend you to take a look at the offers of specialized companies like photonvps.com or vpsland. They have lower pirces being professional providers and having better conditions Also there are companies like apthost.com, whicgh have what you need being highly reliable, affordable and experienced host with excellent reputation.
Thats not true. Im with FutureHosting.com and im paying only $25. Ive been with them for 4 months now and they are great. Look on WebHostingTalk.com for some coupons. @ OP VPS companies usually base their pricing on RAM not diskspace like shared hosting. EDIT: I just realized you want lxadmin... send them a message or go on live chat and im sure you can get a vps around that price your looking for.
You have requirements for the whole dedicated server and ready to pay for the shared account also. So 2 issues do not match
Where do you see a requirement for a dedicated server? He is only asking for 512mb ram with a small diskspace, i think a 10gb space will be enough for him. Its Gigabyte he is asking for and not Terabyte. A small VPS can handle that.
Decent fully managed VPS deals are available from webhostingbuzz.com, this company has offered them with a 10% discount - WHBROCKS. Plans are cheap and full-featured.