$20, or approx £13 is a decent price.
The most I would pay for it is £20, which is approx $30.
I dislike paying upwards of £40 for mainstream branded games. Often times they're overly expensive for a game that I will complete in a relatively short amount of time and possibly never come back to.
And Blockland doesn't have that brand name to it, so I don't feel like I should pay the price of a brand name for something that isn't one.
Blockland might have provided me with countless hours of entertainment over the 4.5 years I've owned it, but that doesn't mean It's worth £40.
If mainstream branded games can charge £40 because it's from EA, or Microsoft Studios or Ubisoft, or whoever, and it won't entertain me for as long as Blockland has/can, then I won't pay the same high price even if Blockland can meet those standards.
And, when you come down to it, there is a fair amount of reliance on 3rd party Modifications, and how many players you can get to join a server, and a fairly slow speed of development.
They make Blockland what it is, but I don't want to pay lots for it.
$20/£13 is a perfect amount.