Depends where you have it installed. But I say install it yourself , its really not difficult. And there are enough people on here that can help you along the way. And I also belive that there is a how to, to help aswell. Istallations at places other than where you bought it (you sometimes get parts installed for free when purchasing them there) ca be expensive I know a HU alone install is $40 at CircuitCity and like $100 for amp and more for them to connect the two foot wires to the subs.
While that amp will power the subs its not ideal. The best amp for those subs would be the Kenwood KAC-9104d....The KFC-W3011 sub is rated at 400w rms and 1200w peak and the KAC-9104d would provide 900wx1 @ 2ohm which would equal out to 450w rms per sub which is great.
As far as doing it yourself vs having someone else do it there is a few ways too look at it...
If you have never done it before the benifits of having a shop do it would be if anything gets broken, scratched, punctured, etc the shop that does it would have to foot the bill vs yourself. Also if you take it say to a Best Buy if you have any problems with it you have over 1000 stores nationwide to take it to who can look at it and fix any issues that were install related. Best Buy would typically charge 70 bucks for an amp install and if you are using a factory radio it would be an additional 69 dollars to purchase and install a line-output converter
it all came in today. my dad was pretty pissed that i spent money cuz i got court on thursday but oh well. for the install i just got a scosch 680 watt install kit a roll of speaker wire and battery terminals. is that all ill need to try it myself?
DK what all came in your kit but you'll need a power wire, ground wire, RCA cable, and speaker wire for the subs. So you should have everything. Not to familiar with this thread but are you making your own box?