I'd say the most valuable item you can get with money are the 1 per day event gacha tickets. They go for 100g a pop whereas buying them more than once per day costs 300g. In 3 days you can get a whole 3 of them which will help you in events.
I'd probably recommend holding onto the tickts for future events though. As a new player this event will be harsh since you have no peronamins to murder the event with. Buy them once per day and use them in a future event instead.