If on the addendum to lease it says, "Lessee shall also have the option to purchase the property after the 6th year at an agreed upon price", do they have to sell me the property?
Question Details: It is a commercial property.
Based on what you write, if there already an agreed-upon price (e.g. one in the lease), they'd have to sell it to you; the wording you quote gives you the option (makes it your choice) so long as a price is already set/determined.
If there is no currently agreed upon price, however, then this provision is meaningless: there has to be a mutually agreed-upon price before you can exercise your option to buy, so if there is no agreed-upon price, there is no option or right to buy the property. All this would then amount to is an invitation to negotiate and see if you can't agree to a price and a sale.