We got this question recently when a startup wanted to establish an e-commerce platform. As the question was in English - and naturally our answer too - and we don't have that much English content in Drontti's site I decided to publish our answer here almost as it was. Why to make things complicated when they're not. We implement only Drupal + Commerce as an e-commerce platform. To be more precise, Drupal Content Management System and the additional Commerce feature set. This is our choice as it's modular, open source, heavy duty platform with good APIs (Application programming interfaces) to various systems. It's not as lightweight or cheap as some of the other options. It's not complicated either nor expensive. The Drupal and Commerce are basically free. The installation, configuration, customisation and possible integration are the things that cost. We have chosen this setup because it offers a great basis for any web solution especially when it comes to e-commerce and multilingual sites. That's why our customers have chosen it as well. If you later on decide - for example - to enhance your customer experience with a blog or want to have a special b2b-extension the platform doesn't limit you. After all the time and money spent that would be nasty, wouldn't it.
"We need nice modern and elegant design" We're basically a software agency. If your site relies on good quality images with rational minimalistic layout we're able to provide what you need (check our frontpage for references). On the other hand if you want to have animations or lot's of image handling or other AD related services then we suggest to have a co-operation partner. We have done it before and we have such advertising agencies to recommend.
"We will need help in online marketing stuff" We're offering basic level Google Adwords and Facebook marketing service when your budget is somewhere around 100-600 € / month. Above that level we recommend to get a specialised service provider.
"We will need a maintenance, what is a monthly price and what is included? If we need new function, what is the hourly rate for what you will work for us? We offer security maintenance for our projects. This means we follow the overall security status, fix the critical issues fast and non-critical issues. All of the other work is done on an hourly basis. We don't give fixed prices per project at all.
Our price per hour differs a bit for different kinds of projects because a basic site, an e-commerce or a custom integration all need different kind of skill set. Describe your project and ask. We do also subcontracting.
"Can you keep the budget?" We try to hit the given estimate as well as possible. Giving estimates about the software platform that we have not implemented ourselves (it's open source <3 ) and that changes constantly (of course! what software area changes more rapidly than the web software?) is just a little easier than using a crystal ball. Additionally a web software project requires mutual commitment - meaning we get the needed material well beforehand and the goal is clear enough in both ends. We'll help with this. The old joke about selling software projects goes something like this: "the buyer doesn't know what (s)he's buying and the seller doesn't know what (s)he's selling". It's at least half true when starting a project so good communication is the key.
The devil is in the details. Often they make up around 10-40% of the total cost and that's why the price tag changes during the project when the details come clearer. To be honest, we want a good predictable project as much as any our customer so that we're able to handle our workload.
"Are you Agile?" Very - but perhaps not in the way you think. We realise that we're definitely too small a company to fulfill the definitions of software development frameworks like Scrum. They're quite strict you know. However, we gladly follow the Agile Software development values:
Observant reader may realise some essential points now.A) It's very nice to follow the Agile Way, B) The end result of the Agile Way is definitely more satisfactory compared to the traditional means, C) It's very difficult to estimate the budget of an Agile project.
As we - Drontti - live to serve our customers and our customers are from small to pretty large companies, we adapt. The main point is to deliver value. For us that means to build a so called Minimum Viable Product (MVP) at first. After that the project continues step by step in the priority order of the features.