Well, Garuda got their 734s from GECAS at 115k - 125k USD a piece for the PK
-GZ* batch... and their GH
* batch was about 100k - 115k USD... per month if you plan to fly them for about 250 a month at a 1H flight to 1 cycle ratio. These were 2002 prices... and aircraft only... They've gone up again.
Bear in mind that it all depends more on your financial backing (lease guarantees etc) that will decide the leasing rate.
If you want to be a broker, then just take a commission on the lease payments and stop at that... why bother going into the airline's market risk ?
Get a top bank to issue an unconditional guarantee for 6 months lease is an absolute minimum (for airlines in Indonesia), otherwise not even the local brokers wanna look at you. Forget the business plan, but the leasing company is more likely to look at relocation, re-registration, re-inspection, and expected in-between customers idle time... And yes, screw the business plan if you got the right financial guarantees...
Maintenance guarantees (regarding standards) from a MX
shop (choose carefully!) makes a lot of difference.
However, that's the condition here... may not be applicable elsewhere.