If you are looking to hire someone to create a custom app for your store, I would recommend checking out the Shopify Experts directory. The directory includes links to third-party professionals who specialize in doing work for merchants on the Shopify platform. I'd suggest reaching out to Experts listed under the "Development and troubleshooting" section.
Victor | Shopify Social Care
It depends on what type of solution you are after. There may be products already available that meet your needs. We operate our own ecommerce data platform where we integration other software with Shopify as well as build custom apps for users that can sit within Shopify or within our platform. We may already have components of what you are after so the development time and cost might be potentially reduced to zero. If you would like to discuss further you can email me at email@example.com