I'm not really interested in building a box. So I'd like to buy one. I'll make sure the box I am buying is very close to the specs required by the manual.

The one I am looking at on ebay is: .85 Cubic Feet

And what it shows in the manual is .75 Cubic Feet, so it's not off by that much.

What are your opinions on buying sealed boxes.

You really have to watch those if you are into aspects of sound quality. Like ask yourself, why is this company able to sell me a complete box, for less then what I am able to build myself. Whats the width of the MDF, is it MDF? will it be a 100% sealed box? because usually on large lines and mass production, quality most likely isn't at the top of that company's list. If you go to your local home hardware, U can get a sheet of 3/4" MDF for about 30$, and they will cut it for free into the slabs you want, just bring the measurements, get wood glue, and your pretty much good to go, any other add ons only minimal would cost about 10$. This will bring you to a good 50$, a bit extra then eBay, however the SQ you get from it will be worth it.

X100 Building your own box is really worth it. Do it yourself, not only will the box sound better and be stronger than any prefab box, you will get the rewarding experience of learning to do a car audio install yourself! It is really hard to screw up a sealed box anyway....

I agree. I assure you most 'low cost' prefab sealed boxes are of fairly poor quality.
Think: If I can make the materials, pay labourers (probably not very much though), build the box, pack it up and ship it from China across the world to North America and sell it for $50 or less and STILL make a profit, how good is the product? (maybe it's assembled here, who knows, either way...).
Maybe you'll be happy? But I'd take my $50 and put it on a sure bet, which is build it yourself.
Cheers.

I would have to echo the sentiments given here already.

I have some friends that have purchased "good deal" pre-fab boxes and they are generally pretty stink.

I am certainly no handyman but I have built several enclosures for people and myself and all have turned out really well. Mind you, there wasnt much "finishing" on them (ie. no carpeting).

Like it was said, buy a sheet of MDF and most places will cut if for you. Buy some wood screws, some wood glue, and some silicone. The box will be much better quality that way.

Just my two cents.
LG