1. Show me some examples of what I can get for my money
2. Charging by the slide encourages a certain kind of presentation style. On the rare occasions that I do keynote presentations I usually have one very spare slide every few seconds, which ends up being thousands of dollars for one presentation.
They should have samples. every designer/design firm has at least some kind of portfolio they can show customers. these people are probably not professionals.
But to be honest, if you go there each slide would be simple; a picture + 3-5 word caption. This service is probably aimed at the clueless business type who do bullet point heavy slides. They would do much better to charge by perceived length of presentation; but this is a subjective metric.
2. Charging by the slide encourages a certain kind of presentation style. On the rare occasions that I do keynote presentations I usually have one very spare slide every few seconds, which ends up being thousands of dollars for one presentation.