I made a minor change to one of my items before, so it should be possible. Just log a support ticket.
Kayako have a free trial on their website. Anyone can sign up and test it if they wish.
You should check out CodeCanyon, there are a number of great ticketing systems for sale. Almost all are cheaper than even one month of Kayako (and you get the source code etc).
It is all about how good the item is.
For an end user $5 doesn’t matter if item A can do the task while item B cannot.
I recently increased the price of one of my applications. The number of sales did drop, but this was also around the time that a number of other similar (cheaper) items were released.
So I went and added some great features and improved the interface. This application is now selling better than before.
Also if an extra $5 means that you can provide better support then your purchasers will prefer this.
I’ve noticed a lot of authors have many many different products and items. I like to keep a small number so that we can make these the best possible products in their category.
Therefore our most expensive product is our top selling product and is also our featured product.
My understanding is that the PHP mysqli extension will be removed in a future version of PHP.
I highly recommend that you use PDO for any PHP project from now on. PDO allows bound parameters (improved security) and it makes it easier to connect to different database systems.
I was writing PHP apps in 2008 with PDO and it has served me well.
EDIT: All my apps here on CodeCanyon use PDO.
Yay 100+ sales of one of my apps! Also yay to a new version just released.
The iPod Touch would work great for this. Same screen and browser.
Why do you want an iPhone without a sim? You could get an iPod Touch for cheaper, the new ones look cool.