I ran across a Reddit thread the other day that was discussing the query: "What's the heaviest thing I can buy for $10.00?"
The ensuing discussion was quite entertaining with all the suggestions - from potatoes, to lead to sand. It even got more philosophical in the suggestion that $10.00 would easily buy you 218 square feet of land (at $2,000/acre). Owning this 218 square feet of land to the center of the earth would give you a hefty weight. But the discussion degenerated into whether the mineral rights went with the land or not. And of course, some land is considerably cheaper.
Next came the concept of valueless, or even negative value items. With some work you could own all the garbage you wanted for free, or even make money taking it. But most of the engaged folks stood fast on the fact that you had to "buy" the material. The one suggesting this stood fast as well and retorted that he'd offer them $1.00 to take the garbage - thus buying it. The rest didn't buy that at all.
There were some other interesting suggestions, but in the end the consensus correct answer was "tap water". At $1.50 per 1000 gallons (offered as the average price for tap water) you would be buying some 55,600 pounds of material. Here in Colby, our household rates for the 1" supply line or less is $1.05 per 1,000 gallons. We'd get 79,492 lbs of water for $10.00! BUT, Colby has a minimum monthly $20 charge (for the first 3,000 thousand gallons) so you couldn't actually buy any water here for $10.00. Most places also have minimum charges.
But all this rhetoric really isn't the point that I've decided to make. This point is that tap water is pretty darn inexpensive, and you can get a lot of product for not very much money. And this discussion thread will undoubtedly lead us off in many different directions...