Personally, I prefer the 'old' style over the 'new' style. IE: the Genesis Silver/Gold B/C over the E-310/330
Even then, the older grills had a deeper firebox which used 13 flavorizer bars instead of 5 on the newer ones.
Most times, a full burner cleaning and maybe an ignitor swap will get you another 5 years of flawless performance.
Really, it's all about the frame and the condition it's in. If the grill sat on a deck, should be very little rust.
As LMichaels said, the deals are there if you keep an eye out (Weber, Webber, BBQ, Barbecue, Barbeque) and Estatesales.net