IS it better to do myself or take it to a shop?  How much should I expect to pay in a shop?   It's for an 09 Corolla

Taking out a strut is usually fairly straightforward.  You'll want to replace them in pairs.



You should probably want to check to see if you can get fully assembled struts, with springs, if you can.  Last time I looked real quick for them, they were about the same price as struts w/o springs and mounts.  You'll need to have an alignment done afterwards, as you'll be changing the camber, and possibly caster, when you replace them.



Struts are generally held to the knuckle with two bolts, and to the body with 3 or 4 bolts.  Disconnecting the swaybar might have to be done, but usually not.  Air tools help.  Breaker bar may be needed unless you've got popeye and spinach handy.



I've replaced all 4 struts in my SRT-4 recently, with coilover adjustable struts, and all urethane bushings.  Drives better than new now.



The only "dangerous" part of replacing struts is if you're reusing the springs.  They're compressed in there, so you'll have to get a spring compressor, clamp it on, then remove the top strut mount to get the spring off.  If the compressor slips off, there is a fair amount of energy stored in the spring when it goes sproing.  

A wrencher can do it...there are tricks on some cars...google "tube 2009 corolla strut replacement" and see what they say.

Monroe Quickstruts are your friend.  

If you can change brake pads, you can do a Struts with these.

I've gone the spring compressor route.  They call the threaded clamp type compressors "Widowmakers" for good reason.

Strut compressors are scary as shit.  I've used them several times in the last few months, and I'm glad I didn't cheap out on them.     I prefer not to do that kind of work, but if it's going to save me a few hundred bucks each time, then I'll just take my time and try not to do anything stupid.

If there was a quick-strut option I would have used it.

I'm doing mine in a few hours.  But I ordered the whole assembly from Rock Auto.  Not only is it a lot safer and easier for me, but I'm getting all new parts instead of just new struts with old springs and such.  

Plus it just means a jack/stands and a socket.

-Emt1581

Coilovers also install like Quickstruts.  I just bought a set for my car.