I had the same problem. I got a price from Monro.. 752.00 for struts and shocks all around, less a 72.00 mail-in rebate. I presume the dealer price would be more.
I took the car to another mechanic who indicated that it needed bushings in the front end also, and identified some engine seal leaks as well. With the potential of well over a thousand dollars in repairs, and the over stated mileage estimates right from the beginning, I just traded it in on a Prius based purely on the economics of keeping it. I really liked the car, and it still ran great without even so must as tire wear given the front end problems, but like you stated, it felt like it was bottoming out.
My suggestion is to have the car looked at by a good mechanic and get an non biased opinion. My Pt had 66,000 miles on it.
Keith
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Selling My Cruiser