£800 is very cheap. £2000 is pretty cheap too for something totally bespoke. Say the company's rate is £50 per hour, that's 40 hours for the £2000 option, and for something totally bespoke, you can't do it in a week. Choosing the right company for you really depends what you want to achieve and where you are at with your business. If you want to get up and running quickly and test the water selling your product, you're probably best off going the template route, so that would be quotes of£800 and under most likely. The companies who have quoted you should be explaining their process to you as well, so you should have a very good understanding of all the steps the project will go through. If they haven't - ask them to do so.