Depends on what you mean by maintain and expensive...... is it a Redline or an NA???? The following list pertains mostly to Redline (turbo), but can happen to NA....
A few things to note.....
Waterpump usually goes around the 50k-60k mark...$1400-$1800 at the dealer (both cars)
HPFP can go after 80k....about $700 at dealer (Redline)
Timing chain after 80k and especially on early '07 as the guides were inferior and weak....$2k+ at dealer.... (Redline)
Valves cake up with carbon as do all DI motors....usually around 80k, some sooner, some later....price: unknown....(Redline)
Camshaft solenoids: any mileage $79/each (2 of them) very easy repair
Oil changes in Redline must be full synthetic...$80
Fuel in Redline must be premium...no regular!!
All of these cars are getting to the age where they're going to need new TPMS sensors...$60/each (Both)
All of the fluids should have been changed and most should be on the second round coming up (brake, steering, trans, diff, oil, coolant) about $1000 (both)
Battery lasts about 4 to 7 years....$100 if you do it yourself...$250 for dealer (Both)
Now this being said, these are what are very common on most of these cars. Is it meant to scare you? No. It's meant to prepare you. I'm the Debbie-Downer of the group and my glass is never full!! Are they fun cars? ABSOLUTELY!!! Would I recommend one? Yes, if it's a second or third car, not primary, and you have the means should something arise.... They are quirky little cars...but what car isn't? Main questions to ask a seller....
Has the waterpump been replaced? If so, when?
Has every oil change been full synthetic? (redline)
If it is a Redline, has it been tuned?
Original battery? (just replaced mine this year and it's an '08)
There are many more things to look for, but in all, they are terrific little cars and a blast to drive...not too mention attention getters...
This information looks WAY scarier than it actually is...
First off, if you have any mechanical know-how, or are good at learning working on this car is very easy and enjoyable. Most of the time.
Water Pump, entire kit to replace yourself(which ive done, easy job) $65 for ACDelco on Amazon.
Timing Chain kit(also did at the same time), $55 ACDelco on Amazon.
Camshaft Solenoids(intake AND exhaust), $25 together on Amazon.
Ive not replaced my Fuel Pump yet, but I do know that performance Autowerks sells an improved one for $160, just came across it recently. and Fuel pumps are VERY easy to replace.
Get an early 07 model like mine and you wont have TPMS to worry about. lol
Fluids...just do yourself, save some money
and im not sure where you are buying your oil...but you can get a 5qt of Royal Purple off Amazon for $35 now, and a wiccs filter, for $10-15. And for me at least, its even cheaper local.
Maintenance is all about what you can do and what you have to have done. Don't be afraid to do research and figure out how to do the work yourself. If you think you can do it, go save some money. I am 100% self taught, and ive had 0 problems doing this work.