I am *ahem* somewhat of an expert on these grills, having bought and restored six in the past two years.
My advice is DON'T BUY NEW! Go to Craigslist! There are at least three beautiful Webers in the Memphis area right now, just begging to be cleaned and restored! One is a fairly recent NG Genesis for $200 and there's a Summit S-470 for less than half retail right now.
A little history lesson: Anything built in the old style (control knobs on the right of the cookbox) were made in america using very thick cast aluminum in the bottom box and heavy gauge steel in the lid and frame. The cookbox and lid are warrantied for 25 years. Only the Summits are made with in the US with high grade materials today. The Genesis line today is made overseas, and although the quality is still outstanding, the lids and cookbox are a lower/thinner grade of material than now.
These things are held together with about 20 1/4-20 bolts. Buy one, knock it apart, pressure wash, repaint with Rustoleum High Temp (Ultra for frame and lid endcaps, basic hightemp for bottom of cookbox), put back together with new SS bolts and new burners ($80) and you've got a grill that will last for 15+ years more. Takes about a day, plus paint cure time. Most of them don't even need that level of restoration. Most grates will clean nicely in your oven cleaning cycle. Weber's customer service is extremely reasonable on parts, too. Much more than most realize.
Currently, I've got a Weber Genesis Platinum Series II (Circa 1990) that is just awesome. Bought it for $75, spent $150 on parts and it's just incredible. Would probably run it forever if I hadn't found a Summit S-620 on Nashville Craigslist last week. That Summit will take about $50 in parts and elbow grease to restore to like new condition.
I've bought and restored four of these as gifts to family, including an older Performer. I LOVE Weber grills!
The others in the same quality range (Viking, Ducane, Jenn Air) are excellent as well, just don't have a ease in finding replacement parts. Most are unobtainium, and what you can find is high $$$. Weber spare parts go back decades for much lower than you'd anticipate, hence why there is such a following for them. Buy your grill, run for 10 years, spend <$100 on new burners and whatnot, run for another 10 years, repeat.