FRANKFURT (Reuters) - SunExpress, a joint venture between Lufthansa (>> Deutsche Lufthansa AG) and Turkish Airlines (>> Turk Hava Yollari AO), said it was placing an order for 50 Boeing (>> The Boeing Company) jets, worth $4.5 billion at list prices.

The order includes 40 firm orders and 10 options, the firm said in a statement on Wednesday, and comprises 25 Next Generation 737-800 and 15 737-8 Max jets.

SunExpress currently leases the majority of its Boeing-only fleet and owns just 6 of the 63 planes in its fleet. It said that the current economic environment, where financing is easy to come by, means it makes more sense to own planes than to lease them.

"With this decision we are securing our expansion in both Turkey and in Europe," SunExpress managing director Paul Schwaiger said in a statement.

The new planes will be delivered between 2015 and 2021.

(Reporting by Victoria Bryan; Editing by Maria Sheahan)