As I said at one of the forums, if you plan your website to be a hobbyist one or a spamming one, by all means, use any of the cheap shared hosting services out there. It’s unreliable and non-business-worthy but it’s cheap, and subsequently lots of crap sites are hosted there. It will gain you no SEO advantage from an IP point of view and your sites will be down multiple times a week.
If you value your time spent on developing and promoting your website, if you want your online business to grow in a good neighborhood recognizable by Google, if you hate overselling as I do, if you would love a honest undersold host and a clean dedicated server, you should come to Jointly Hosted, the non-profit host dream for friendly and ethical people who deserve a powerful, clean server to host their endeavors.
256MB being the startup plan from most VPS providers will be no better than a shared hosting plan from affordable hosting providers. 384MB may seem to be a 128MB extra but actually just slightly more.
As a result of the nature of VPS, an entire operating system (such as Linux distributions: Ubuntu, Debian or Centos, and so forth) resides in it with a complete web server package: Apache, PHP, MySQL and potentially a lot of necessary modules and extensions, making the mere hosting slice of 256MB a frugal choice to cover all the overheads, much like the sunk cost in Economics. It is after the threshold of 256MB that every additional MB of RAM you purchase will be consumed by your own websites rather than by the system. Well, not precisely all of 256MB will be used for the system, but you are left with like 50MB – 100MB from the whole 256MB pie after installing everything WWW and getting your slice ready for websites.
So if you are going to switch to a VPS, make sure you board on at least 512MB memeory for a start or it won’t be worth the while and it may just be good enough to spread your sites across various shared hosting plans (preferrably from various distant hosting comapnies) for some SEO advantage.