^^ Just to clarity, I meant to say "I'm NOT into waiting indefinitely." That was a typo. (Edited accordingly)
The usual rule for a contract for sale (or a contract of ANY kind) is that execution of the contract occurs within a specific time period. If you offer a contract that says "I'll execute my end of the contract whenever I choose to do so, no matter how distant into the future", that's not a legal contract, and no buyer is bound to honor it.
In non-legal parlance: Shit or get off the pot.
If I were the forum moderator, I'd delete this thread if the seller doesn't respond soon.