One thing that has changed for me during the past couple of years is that I have been negotiating on purchases and sales via text message much more than in prior years. I have closed a few deals on both sides via text message, and it seems to be more acceptable these days than in prior years.
On my Embrace.com price request inquiry form, I have an optional field for the prospect to leave a phone number. Typically, I will send a canned reply via email with the price of the domain name and a bit of a sales pitch. If the prospect left a contact phone number, I will usually send a text message to let them know their request was received and a reply was sent.