HI There,
First I am sorry to hear about your past experience.
Please let me know what kind of website you wanted to build? And can you tell me the reason why you only need it on shopify. I am asking this, because it looks like its your new shop and you wanted to have some custom functionality into it, as related to pricing, taxes etc. Normally shopify is a good platform for straight products, although they do provide feature for custom pricing and attributes but when you want to expand website functionality shopify/ bigcommerce, etc are not a good option. that is they an advice. If you still want it on shopify, please share you specs and I will straight away tells you if its possible or not.
And I have no issue with payment, once project is awarded you can create milestone and release it at the end of the project.
You can check my sample work at:
https://www.freelancer.com/u/extreamcode.html
regards,
Asad Sajjad