A website budget depends on the action it should support: explaining an offer, receiving a contextual enquiry, selling or providing access to a service. Define one primary action and its audience before comparing quotes.
A store sells a catalogue managed by your organization. A marketplace brings together multiple sellers and buyers. The central difference is responsibility: who lists, sells, invoices, fulfils and refunds?
A web application opens in a browser. A mobile application is usually distributed through a platform or device-specific channel. Start with the work to be done, usage frequency and user context.
Start with a precise question: pass website enquiries, receive orders, publish stock or display customer tracking? A bounded workflow makes it possible to assess value and constraints before choosing a technical solution.