In terms of settlement, you need to ask yourself what you think an attorney can reasonably negotiate for you (not some pie in the sky idea where Navisite leaves you alone forever without collecting a dime because that's not going to happen....but the best deal a good negotiator would get you based on all the facts in play)
Then add to that number what you'll have to pay in attorney fees.
If that total number is more than the deal they're offering, you should take the deal.
FYI, get a full release in writing before sending them the funds. Should be a standard language form that the attorney has on hand that releases you from any further obligation to the company if you pay $X amount by X date.
DON'T send any money until you've received a letter like that signed by an officer of the company or their legal counsel. Otherwise the money you send could be considered a "payment towards the total you owe"
