Most W124s are in insurance Group 16. You may be able to cover them on a classic policy, particularly if you have another vehicle as your "main" car. Classic policies are generally much cheaper than ordinary insurance and enable you to set an agreed value, something that the majority of ordinary policies will not

Insurance companies may refuse to pay out the market value of a W124 as they use a "Book" value that has no relevance to market values. In theory this shortfall could be covered by a Gap policy but most Gap policies we've looked at don't offer appropriate cover. You are recommended to use a good broker and arrange appropriate cover with an agreed value. It's not possible to generalise on insurance costs