Most of the cheap hosting options for your ecommerce web hosting are on shared servers and you will need to make the decision whether you can get enough out of the shared server to be able to run your business smoothly.
A problem with a shared server is that you can only have a set amount of server space, which can limit the amount that you are able to do within your server side programming. This means that you could find that you are limited to the creation of your shopping carts through PHP programming, which could seriously limit your business. You may be able to find some website hosting companies out there that are able to offer accounts specifically for ecommerce reasons.
There are a lot of things that you need to consider when you are looking into cheaper hosting options. While it will make it easier for you to make a profit on your business, you may find that you need to pay extras when it comes to running your website exactly how you need to.