This really depends on the complexities of the estate. Most probate attorneys charge hourly for assisting with an estate administration. So, how much they end up costing depends on how complicated the estate's assets are and whether everyone involved in the estate administration is cooperative. You should consult a local probate attorney. Most attorneys will be able to give you a good estimate of how much it will cost once they learn more about the assets of the estate and the issues that the estate may face.
If you are appointed as Executor or Administrator of the estate by the clerk of court, you can contact the bank and request statements for all of the accounts owned by the person who passed away.
Talk to lawyers about their fees before you hire and then it should be memorialized in a written fee agreement.
There used to be percentage fee schedules but those have mostly gone by the wayside now, and much estate advice is dispensed by the hour. So, depending on the problems, it could be just as much or a smaller sized estate, or as much as, or more, not depending on the values per se, but the complexities and difficulties. Of course more assets almost always means more work maintaining them. But all of that goes into a reasonable legal fee.