As someone who has been in IT consultasntcy and software for over 30 years and self employed for the last 18 a few things here.
If you are a coder then your skills are a commodity and easily replaced with someone/something else, yes there is a learning curve in regards to the company and clients but not something that really factors in. If on the business/client side often the realtionship and numbers of points you bring in factors greatly. Do not let your ego and appraisal of your skill set guide your feelings if they say nice to know you, last thing you want to do is burn a bridge period. I don't know hwo many times a client or colleague of a client has asked me abut someone and I've worked with years ago and they left a not so favorable light.
Now on to business. No one like to be demanded to or bargained with, Me personally if someone says here counter this offer, unless they have a role that just cannot be replaced in the next 30 days it's walking time. Shows a form of unhappiness, if unhappy talk to your manager first then pursue other opportunities not the other way.
As far as the recruiter goes, do you only have 3 years total in the industry? The reason I ask is to assess your relationship with and type of recruiter we are talking about, I do not deal with DICE, Linkedin etc type of recruiters at all simply because they are just high pressure saels people. Expect this person to pressure you into deciding now and giving you the "chicken little"
treatment IE if you don't say yes now the offer will get pulled. If might be best to just blow off responding for a few hours to decide or gauge your interest.
As far as the whole thing goes, bottom line if you interviewed there was enough of a reason to be looking. I'll tell you right now money is not the most important thing in the software biz at your stage, having a job that keeps you relevant in the market, your skills saleable and a career path are far more important at this early stage in life (I'm assuming you are younger @25 or so basd on your experience). Money will come later when your skill set and expertise justify, build your career first would be my advice.