How much does it cost to put second hand engine?

Hello there, I was looking at this area in bangkok chiang kong? where they sell heaps of second hand engines.

I asked them about the price of exact same engine of my current L15A 1500cc honda and they quoted 15,000THB. They say its imported fom japan.

they didnt exactly reply about the warranty, but they say they will start the engine if im interested.

they do not do the install.

Im really new to this and is the price quoted seems alright?

also how much would the average installation cost? Im assuming if its the same engine, they just need to unplug the wires and stuff the biggies in and plugin again?

i read somewhere the toyota V8 5000cc engine can be purchsed around 50K THB.

my car is 1500cc, so it wouldnt be possible to put this biggie in? If possible, all the parts like pumps and stuff needs to be matched to the 5000cc engine?