Welcome to our forum.
1500.00 is reasonable if it's in good shape. Not great that it's been sitting empty for 2 years, hope it runs for you, as far as leaking it may not show itself till the spa has been running for awhile unless it's in the equipment area..
Tell them to have the tub curbside so you can pick it up. It's not your problem to get it out of their backyard.
Pass on it!