Headers you can get cheap ones but a mechanic is gonna charge you probably 7-8 hours to do it if they will even do it. Cam install will probably be about the same. Rockers like 3-4 hours. If you do them yourself you'll save a ton of money.
no need for a lift. I do all my own work with a jack and some jack stands in my garage at home. Rockers are super easy anyone could do them. Headers are a little more involved and a cam isn't something that should be done without a knowledge of the inner workings of the motor.
I know there is a header one. Billboost37 started it. I'm not sure about rockers but on those the hardest part is getting the valve covers off.
I ran zzp modded 1.9 rockers with no problems for 30K miles. You wouldn't need any other parts or a tune but you'll benefit from it.
Headers and rockers probably won't add any noticeable power, but you would be able to run a smaller pulley, and that is where you will notice an increase in power.