That's really a 'how long is a piece of string' question, as it's not only the value of the estate but the complexity of it that's important. (e.g. Are there any pension funds involved? Is the deceased person's tax situation up to date? Are there any stocks and shares involved).
Complex estates can cost large amounts to sort out. (My friend has property in two countries and bank accounts in four. Her Italian solicitor has agreed to handle her estate for a pre-set fee of €20,000!).
However it's likely that the estate involved will be very simple but I'd not be surprised if the solicitor's fees consumed 10% to 20% of it. Perhaps the executor can find a friend, who feels more confident in such matters, to guide him/her through what is usually no more than a simple bit of form-filling? (I've done it myself. It's a doddle!). It could save a great deal of money!