If it's a good script with multiple options, $4.99 should be an easy sell. $10 (as someone suggested) is the cost of much more complex script like imps, blast furnance, etc.
Some options to think about:
- Multiple houses
- Butler support
- Oak door support
On another note, should do free trials of 24hr so people can test and see if they want to purchase it.. or you can release it for free as like a beta until you feel there are no bugs and is worthy to be considered a premium script. This is also good because people will be more inclined to buy it since they are "hooked on it" if you get what I mean.
Good luck, and grats on release. Personally won't use this since I would just want 50