Buy time and do the right legal things.
Structure your holding lease to buy you time and optionality. Outline a clear payment schedule, and terms for the right to purchase. Use a verified escrow agent to facilitate the transaction (we use escrow.com).
Final words of advice:
Don’t be afraid of a high purchase price in 5 to 10 years in a lease-to-own arrangement. At the risk of sounding stoic, it’s likely that it won’t matter in the end, no matter which direction your companies goes. But with a great domain name, organic traffic and SEO is on your side.