Can I buy a lab-grown diamond ring for under $3,000?
Antiquecut
Yes. Antiquecut offers a wide selection of lab-grown diamond rings priced under $3,000, including oval, pear, marquise, cushion, emerald, and radiant-cut designs. Many options combine larger center stones with detailed settings while staying within the budget. 
visit : https://www.antiquecut.com/collections/lab-grown-diamond-rings-under-3000