If your site grows in size over the years, you may need to upgrade your account. This is not very likely unless you have over 35,000 visitors a month which is hard to do. If you do grow this big, you will probably make enough money off the site from advertisements to pay for the server upgrade so do not worry.
If you want to upgrade your hosting account, you can always opt for cloud hosting which goes for about $50 a month. This is a little to much to pay for hosting if you are just starting off and do not need to use the extra bandwidth.
If you really need to go for a high priced option as your site has just exploded in traffic, then you may want to go with a dedicated server. This is a solution for only the high end websites out there. They usually start for around $100 a month which is over a 2000% increase in price from a shared hosting account. If you need a dedicated server, congratulations on building a successful website!
Whenever you signup for a hosting account, make sure that you are getting a company that will give you the features you need to run a successful site. This means that you will need to test your site and set it up at different times throughout the day. High traffic times are generally in the morning and in the afternoon so many sure you test those times to get the best idea of the servers performance.
When you test a server at first, your first impression is probably a good representation of what the rest of your experience will be like. If you are having issues from the beginning, it probably will not get much better so I would suggest you look for another hosting account and get your money back. Good luck finding a host that works as well as the ones I am currently working with.
