Lots of places mention that traveling to New England was so expensive that many people became indentured servants to get across, but I couldn't find a place that actually says how expensive it was.
It seems that the Massachusetts Bay company had a rule setting out some costs and the limits on the number of passengers that ships could carry.
- A ship of two hundred tons should not carry more than one hundred passengers (other ships adhered to the same proportions).
- The cost of passage was 5 pounds sterling for an adult (and 4 pounds for a ton of goods).
- 5 pounds sterling for an adult
- Children over the age of 12 were carried at half cost (2 pounds and 10 shillings)
- Children under 12 were carried free of charge
- 10 pounds sterling for a horse
- 3 pounds per ton of freight
It seems that this cost of passage for an adult is also comparable with the cost of passage of 5 pounds for an adult on the Mayflower in 1620.
Comparing the values of money in the past with modern values is fraught with difficulties. The Measuring Worth site has a simple-to-use calculator that computes the modern equivalent of past monetary amounts, using five different measures, that can often help gain some insight into the true "cost" of something in the past.