A simple will cost you about $200-250.
Wills in the Dominican Republic are good for: (a) if you don't want to leave everything to your children (you can dispose freely of a portion of your estate), (b) if you want to leave one or several of your children a bigger portion of the estate than to the other children (in effect giving the disposable portion to these "favorites", (c) if you don't want your moveable assets (cash, stocks, bonds, etc.) to be included after your death in your children's community assets, (d) for funeral arrangements, etc.