The cost depends on multiple factors. The list includes but is not limited to the following only:
Your project requirements and business goals. Like the features you want in your website.T
he other is the level of complexity involved in your project.
The Amount of work your project needs.
The kind of software/extensions your project needs.
I think i can suggest your a team of Magento development services that you can hire and their cost will not burn a big hole into your pocket. Thanks to their development practices.
They are SoftProdigy, a team of Magento certified and experienced developers. SoftProdigy is a twice Clutch recognized eCommerce development service provider.
I know all this about the company because i had a chance to work closely with their team for my clients. They delivered bug-free work to clients. My clients were very happy with that.
I am leaving a couple of links below liteblue to help you reach their website and check the quality of their services. You can find these links in the reference section.