How much would you pay for an ecommerce app?

I'm a software developer and I've recently developed an ecommerce smartphone application that can work with any existing ecommerce website.

It is an ecommerce shopping application similar to Amazon's and eBay’s smartphone apps but for existing online stores who want their own smartphone application.

Our goal is to help you increase revenue and customer retention through the repeated customer engagement that only a smartphone application can provide.

I’m giving the application away to any ecommerce website owner for any voluntary monetary contribution they can give me so that I can gain testimonials before I launch.

On my part, I’d like to reserve the right to share the services I perform for your business on my portfolio, and to also mention your business name.

If anyone here wants an ecommerce smartphone application for their business, then I'd love to work with you, I will only be doing this for a limited number of businesses before I launch.

It’s not free however, you can pay any amount you think is reasonable.