Just gonna let ya know, unless you’re looking for something extremely basic, you’re gonna need to hike up the pricing. Most rollercoasters on Roblox are gonna rely at least partially on the physics system in place which can be tricky, and then you have the fact that rollercoasters are pretty tricky to create & look good.
Combine all that with such a short deadline (5 days) and you’re looking at a pretty big price tag.
Also consider:
Include more about how you would be paying. (Is it group funds?)
Show the small island & give sizing requirements so we know how big is your “small island”
To be on the DevForum, you are supposed to be 13 or older. So a bit of a redundant requirement.