Even with the help of REW, the last time I tweaked my subs it took the better part of a day - several hours - before I was satisfied with the results. I think you'd own me a months' worth of pizza and beer for that much time and effort!
Not that I would even like that much pizza and beer. The point is, anyone can come out and deliver a graph that "looks good," but only you can determine if it actually sounds good to you, because each room and each pair of ears is different. And it may take a few days or weeks, after your benefactor is long gone with his laptop and your pizza, to make that determination. I fiddled with my EQ and REW off and on for a year the first time around before I got what I felt was awesome sounding bass.
So, it's really best to do this yourself. As brucek mentioned, you already have a computer. We're giving you what's arguably the most important component - REW - for free. All you need is an SPL meter and the cheapest duplex sound card you can find (assuming your computer doesn't already have one), both of which you can eBay.
Regards,
Wayne