I think this is an excellent buy, provided that the telescope is mechanically sound and that its mirror has not been degraded. You need to check that its mounting is still 'tight' and wobble-free. Make certain that when you 'lock' the two axis in place to look at an object in the sky, that there is no slippage. The mirror surfaces (primary and secondary) are clean and show no signs of tarnish. The last thing you want is a 4.5-inch telescope with the light gathering ability of a 2-inch telescope.
If possible, you should take the telescope out for a test drive and look at a few bright stars under high magnification. The images should be round from the center of the field to the edge, otherwise the optical system has serious imperfections that will rob you of clarity. You do not know how the telescope's previous owner treated this telescope, and severe mishandling often can show up in 'warped' or degraded optical performance.