Well, you know what I recommend.
Here are a few things to consider:
- Is warranty covered locally
- Can the amp be serviced locally (ie: Arc audio)
- Will the power from the 2-channels effectively be able to power your sub
The Infinity

Perfect is an 'ok' sub but it has an aging design and there are many others that are better for the price. The IDQ is ok but again, there are many others to consider.
Also, be sure to buy locally so your sub, amp and install are covered under warranty. Another thing is to ensure that the sub enclosure be custom built or at least within reasonable pre-fab specs for the sub.
My suggestion is the DD 1510 and DD S4 4-channel amplifier. 2X 100 and 2X200 will be enough to power your entire system. Come and listen to one of the three that we have in our cars.