Let's say I want to sell you something for $100, like a front-row ticket to a baseball game or concert.
In order for this transaction to happen, we would need two things – otherwise, you'd opt to pass up the offer:
1) You would have to be convinced that the ticket (or, perhaps another way to say it, the experience of going to see the event) was worth $100 to you.
2) You would need to have the funds available. In other words, you might be willing to pay $200 to go to the event, but, if you only have $50 left in your bank account, you might have to pass up the offer, even if you were convinced it was a great deal.
Near as I can tell, the sentence:
It was easy to prove $1 of value and there was a low threshold to purchase.
is touching on both of these economic ideas, saying that they are both easy to achieve because the amount is so low:
Easy to prove $1 of value means it won't take a lot of persuasion to convince you that whatever is being sold is indeed worth the token amount you are paying for it.
a low threshold to purchase means you don't need to have a lot of money in the bank in order to buy something at such a low price. Only the truly destitute and penniless would be prohibited by cost.