Brad, I suggest you put a few bucks back into the grill that served you so well for 20 years and march on. You can replace the burners, flavorizer bars, cooking grates and igniter for bit over $100 with all good quality Stainless steel parts. A quick clean on the inside and you basically have a new grill with parts that will last you many years to come.
Or you can do a full restore to that silver b and basically have a brand new grill and it would cost you less than 1/4 what a new one would cost and most likely last longer as well...
Just check some of the rehab threads on here.
But, if you really want to replace it with a new Weber Genesis, I suggest you grab the style with the open frame underneath. The cabinet style grills turn to rust buckets inside in just a few years.
There is a market for you old grill, but unless you really clean it up and everything is working well, it is under $100 most likely.