Pricing by Transaction

Hi to all,

for small Buisness Users i read about a Transaction Limit of 150 per year.  Does it means that 1 Document sended are 1 Transaction?   Or is only a signed Document a Transacation?

We like to use it to send Qoutes out and if the client lik th qoute they can sign and accept.  But if he dont like he cancel.  But if a cancel or a non responder counts like a transaction it is to expensive for that matter.

anyone have a answear on this
thanks