Not trying to be snippy but if the cost of weights is a problem, you are probably in the wrong sport. Maybe the cheapest item in your dive kit. On most diving trips, the weights and "renting" a bottle are included. Hold off on buying them for a while until needed and look hard into soft weights as they are generally more comfortable, especially if you drop one on your toe or your buddy. Most of us accumulate many weights that are rarely used. I probably have 100 pounds in the garage between myself and my wife. I use them for skydiving too.