When I first had my IS200 it had 6k on the clock and the garage advised me to go up in incriments of +1k to get the sequencing back, e.g. I had it serviced at 17k, 28k, 39k and then 40k onwards.
I've just had my 60k service, provided my own spark plugs - iridium denso ik20 off ebay from the us for £35, supplied my own air filter k&n - £40 and fitted my own aircon filter. I paid £340 with LOC discount. I didn't supply my own oil - but I probably will next time as they charged my £35
If you do all of the above you should expect to pay £300-£350 for the service - not bad eh!
Oh, you can fit the spark plugs if you want and that will drop the cost of the service by 1 hours labour. I chose to have them fitted by the dealer.
Just reading back your thead, to be honest mate if it was me I would have a minor service as your car is out of warranty the dealer won't be bothered and probably won't stamp the book and get the 60k service next year - as your car has only done 45k the plugs will be ok (good for 60k at the least)!
Good luck!