Should I take their offer or should I wait for them to sort the
First, part of me is tempted to know what types of objects they would offer you. I mean if there is resale value in them, maybe taking them and selling them is not a bad idea.
But that is only my curiosity. I would not accept any objects as payment for work done for any reason.
Why? Easy. The second you accept those objects, regardless of value, they will consider the contract finalized and executed. Yes, you say you need to provide a document confirming payment was received but that sounds quite bass ackwards if you ask me.
In the great scheme of things I believe you need to invoice them for money owed and do so with a clear legal threat. Depending on the amount and where you are located you can probably take them to small claims court on your own without having to hire a lawyer.
And depending on where you are located, payment not received within 30 days might be implied by contract law. Meaning even without a contract you have a legal claim for payment for work done if you can prove work was completed and delivered by a certain date.
That said this whole scenario is a perfect example of why you need a contract upfront before any work is done and why you should do a 50/50 split on the contract.
A 50/50 split is exactly what it sounds like: 50% of the agreed fee upfront before work is done and 50% on delivery of the final product. That way if somehow you run into nonsense in the process of getting the second 50% remitted you have the option to walk away from the client.