Contact the ORIGINAL creditor (not the collection agency).
Tell them that you are ready to send them a Certified check (or money order) to pay in full. Make sure that they give you a "Paid if Full" statement for the check. Obviously this can best be done if the original creditor is located in your town.
(The collection agency is an agent of the original creditor and makes their money by taking a percentage of what they manage to recover from you. Since you are contacting the original creditor they will be glad to take your payment, it saves them the percentage they would have paid to the agent).
As for the amount, since you have received notice of suit, there is a strong chance that the amount you will have to pay will be more than that owed. The difference should be equal to the legal expenses and court fees incurred to handle the lawsuit. Make sure that the Original creditor files a "Non-Suit" on the legal action (basically, this stops further legal action since the cause of action, the overdue bill, has been paid).
Hope that this helps....
