Well, this is your very first post, here on T4R.org, so we do not know much about you, your rig, your technical skill level for DIY, or your level of enthusiasm toward said vehicle, which makes for offering you advice, damned difficult if not impossible. Most of us here on T4R.org love our vehicles, and therefore, will usually go about doing whatever we have to do to keep them on the road as it is a labor of love. The prices you quoted, I am assuming, are parts plus labor. Most of here, would do said labor ourselves. Your runner has not hit 100k miles yet, and therefore, is not even halfway through its life. Your shock "hydrolic (hydraulic) system" is actually called XREAS. Typical life span of XREAS is about 110k - 130k miles. Replacement of XREAS is not cost affective and thus most people here on T4R.org, simply replace with standard shocks and springs. This would cost you around $500.00 - $600.00 if you do it yourself. Not sure about the cost of the catalytic converters, but I am confident that it would be HALF of the dollar amount that you quoted, if you went aftermarket and did the labor yourself.
Anyway, assuming that you, and the previous owner of your Runner took good care of it, you have a vehicle that has at least another six to 10 years of life, if you are willing to care for it. And when put like that, even $5,500.00 in repairs doesn't sound that awful. Besides, a new Runner is going to cost you damned near $40k.
