First, So what's the material involved? Do you have (say) Groco 1-1/2" thru hulls out of bronze or are they Marelon? What size makes a difference on material. The yard's cost varies (say 75% of the retail, for starting purposes -- if you include a little for misc. for some bedding and sealant, for example). As with many things, size matters a lot with respect to the cost of the material -- less with the labor component.

Secondly, are you replacing the whole thru-hull or just the valve -- i.e., leaving a stem in place. That's a big difference in time that you'd assume.

You want to make sure, if you use plastic that it's MARALON (a Forespar, product); and if you're using a metal fitting, then I'd go with Groco bronze fittings -- but there are others. We have both on our J/Boat. The Maralon fitting are fine as long as you don't have them in a place where you're going to be mechanically abusing them. They don't corrode and are more forgiving of lubrication issues. If you go with metal, then be careful that you have a really good thru-hull.

So before everyone jumps in to say: That's a reasonable price, or that's an easy job, what are you getting done???

[P.S. -- my "Blink" reaction was the same as a lot of others...sounds like a good deal. Then I started to second guess my reaction. Help us with it.