I was on the planning committee for our 20th last summer and we really had to work to keep our costs down. A bunch of stuff happened where we didn't have any money in our account, and on our 5th reunion we could only afford a kegger in a field.

Then nobody was interested in a 10th or 15th, so a few of us got together for the 20th and put together bake sales and things like that to raise money for it.
We got a decent local country club in town where they hold 90% of the reunions. I think when it was all said and done we charged around $30 per person, and even then we felt like that was a bit much. We wanted to make sure to have enough in the bank when the reunion was over, so for our 25th we can do a little more for it.
We had a few complaints from a couple of people about it being sort of "low-rent," but everyone else thought it worked out wonderfully. We're in a small town, so I don't know what on earth they expected, as we chose the nicest place available!
What all is included in your $170? It could very well end up being that expensive, but I don't know what type of area you live in or whatnot, or what your reunion committee had to work with. We were able to do
a lot of things at cost (like our printing), which really kept the price down.