There are lots of good thoughts here. If the only thing is to make you more marketable, then consider if there isn't something else less time and money consuming that would give you more.

I think college has more to offer, but it really depends on what you want out of it and how hard you want to work.

At the moment, the economy is booming. You could always go back to school during the next downturn. When it's raining soup, put out your bowl and all that.

I have seen professional doors shut because of a lack of a degree, or a lack of a masters, or a phd. It all depends on what you want and what tradeoffs you're willing to make.