I like to consider things in terms of entertainment quotient (EQ), which is a scientific-sounding economic term that I just made up but describes a concept I've used for a long time. The idea goes like this. Consider the cost, C, of a single parcel of entertainment, and the total duration, D, of the entertainment derived from that parcel. We must include an awesomenitude coefficient, A. The value of A ranges from 0 to effectively infinite, but the coefficient for a particular type of entertainment varies from person to person. (For me, for instance, 0 is "watching a historical reenactment of the second Council of Nicaea performed in Latin by octogenarians," and "HOLY FUCK I'M ON THE FUCKING SURFACE OF MARS I DON'T CARE IF I DIE HERE 'CAUSE I'LL DIE HAPPY" is effectively infinite, with online gaming in general scoring a solid 10.)
The entertainment quotient, then, is EQ = AD/C. I usually measure this in hours per dollar. I'll omit discussion of the procrastination coefficient (which increases the value of C) and the advertising correction (which decreases the value of D) for the sake of (relative) brevity and not making anything else up.*
Of course, an individual parcel of entertainment may have varying A, D, and C. A midnight showing of the next Star Wars movie is going to have higher values of all three than waiting until it hits DVD or Netflix. Nonetheless, a good action flick in the theater has, for me, an EQ of about (10)(2)/(15) = 1.33 hours per dollar. A month of WOW, though, has an EQ of (10)(30)/(15) = 20 hours per dollar. A good, cheap video game that entertains me for a lot of hours (Minecraft and Spacechem have done this to/for me) might have EQs in the 50+ range.
Isotropic has an EQ of infinity, as do various free online entertainments and, for that matter, television. And I think this is part of the problem; isotropic has been a sweet deal. Goko, of course, will have a lower EQ than Isotropic... but that EQ will increase over time as you play more. Assuming comparable A for, say, wero, his EQ is probably already into the 100+ range just based on his videos.
Now that Goko is an approximately equivalent experience to Iso, I see Goko as a pretty good deal.
Dondon: Winning those games at tournaments has its own opportunity costs involved, as does obtaining them as gifts or using friends' sets.
*The full equation is EQ = [A(1-m)]/[C + pID], where m is the marketing correction, p is the procrastination factor, and I is income/hr. For the record, the awesomenitude coefficient for making things like this up is also in the 10 range for me.