Sorry, missed this comment. Thanks you! The domain was ~$120 USD, if I recall correctly. Still a lot for a domain, but not as much as I would have expected for a premium domain.
I started writing Attendize about 11 years ago when I had very little professional experience. As a result, the code is quite terrible and difficult to customize and extend.
With Hi.Events, I designed the API first, making it more robust and open to extension. One of the most frequent requests for Attendize was for more flexible ticketing options, such as ticket tiers and donation tickets. I've incorporated these features into Hi.Events, along with much more powerful attendee management and customization features.
I previously created Attendize, another popular open source ticketing platform. I sold it back in 2018, and unfortunately the new owners have abandoned it. So I decided to create a better alternative.
Overall it took me the lion's share of a year. Mostly working for a couple of hours in the evenings.
This is actually something that I spent a lot of time trying to get right. Currently when a user selects their tickets and clicks 'Checkout', all other sessions they have open will be cancelled and their reserved tickets released.
This still doesn't stop people from completing the checkout process and then starting again though. It's a tricky thing to prevent as most preventative measures are easily circumvented by users.
We're still in alpha, but we'll have a beta cloud version soon, so be sure to check back in a few months!