RX8Club.com - Need some help please : Manifold Shutter valvue, coils and spark plugs

Hello all,
Thanks for taking a look at my question. I do not know a whole lot about RX8's, but my fiance owns one (2005) and we have a major problem. Last week we were having trouble starting it and knew it wasn't the battery because it was just replaced...so we had to get it towed to a repair shop. Repair shop said it was getting spark, but their computer read it was getting no compression and it blew a head gasket. So with that in mind, we towed it to the dealer since that should be covered under the warranty extension of 8 years 100,00 miles, right? Well the lady from Mazda called me and said that their computer is coming up with code P270 which supposedly means the manifold shutter valve is open. So since that is not covered under the warranty extension, she said they would have to replace that, along with the coils ($803.97), the spark plugs (which she said were $200 a pop) and the battery (which is still under warranty) for a grand total of $1700 something BEFORE they will even look into the engine and the stuff that is covered under the warranty extension. Any suggestions/advice? $200 bucks a spark plug (even with labor) seems steep as I look online and OEM spark plugs are around $25. She might have said the spark plug wires need to be replaced too. Please help!! I am greatful for any help you can give me/us. God Bless.