You haven't given much info. Do you know much about internet traffic? You might be overestimating the organic reach of your domain.

That being said, it's not too bad a deal, you are only out $2K if you have a taste and the domain doesn't deliver.

BUT cut out the equity piece. These type of shareholders are at best pure dead weight and at worst a pain in the ass.

One other note, even with a contract, there are ways the seller can screw you (eg. changing their bank acct details & going incommunicado) so if you are leasing make sure the domain is controlled by a neutral 3rd party for the lease term so you are protected if someone with a better offer comes along.