Since leasing is based on the purchase price, considering you're leasing through Lexus, all other factors should be the same. So, find out the Invoice on your particular model and see how close you can buy the car to Invoice. Then, ask them to do your lease based on that price and make sure you get quotes for 36,39,42,48 months and 12 and 15k miles so you can figure out which option is the smartest one.
Good luck and here's an estimate on what to expect:
$40,000 RX330 will cost about $550 a month with $1500 due at signing.
For every 1 thousand dollars less than $40,000 , expect to lower that payment by about $22 a month.
Shop around and good luck!