Mike, being naturally cautious (as tight as a duck's arse) I would ask myself just how much use I was going to get out of the camera once the initial "fun" had worn off, and how long it would be sitting in a cupboard doing bugger-all aftaerward.  I would look more carefully at hiring one (OK, you have to give it back, but you're going to get a far better quality tool) or, al;ternatively, what's goping to give me the best resale value, so I could recoup some or all of my putlay be reselling the camera.

With the rental situation, you need to sit down and plan exactly what your tasks would be, them write them down, make a plan.  That's also a good method for working out the longevity of your shiny new camera.  Work out what you need done, and then employ somebody with the same technology to do the work for you.  You can show him/her your FLIR images (which he/she will no doubt replicate) and ask for the requisite "after" shots on completion of the work.

Just laying out an alternative for you, on a subject about which I know nothing, in the long-established tradition of forums everywhere. 

I've been using TC for many years, they are invaluable when you can't locate a fault on a circuit board, so by loking for hot spots you can 'see' shorts and overloads we have a FLIR E8-XT quite invaluable.

This year the energy prices had me thinking hard.
The very cold temperatures surprised me as it seems much colder than previous

Jeez Mike, that's a lot of money. I thought we were bad at £250. Going up again next year I believe