I'm on my third restore..
The first was EASY - it is a 2 burner silver genesis
It was free so I had a simple start. All it needed was some cleaning, new crossover burner, Flavorizer bars and a new ignitor.
So I have about $55 in it... I went with the less expensive RiversEdgeProducts bars off ebay.
It works great- gets to 450 degrees pretty quick.
My second one is a Red Genesis 3000 I got for $35
I got lucky and all it needed was the Flavorizer bars - Its the deep box with 13 bars and were $65 from RiversEdge
Its a 3 burner and gets to $550 quick.
Finally I have a Genesis 3000 with the side burner - I had been looking for this grill on caigs list for months and up I snatched the first one I saw.
Ultimately I overpaid $100 ;-( It looked like it was in a lot better shape than it really was. After cleaning it up I realised i should have paid under $50
But this one is a keeper and i wanted to do it right.
New parts from weber - bottom side rails for the catch pan, new catch pan assembly, new left side table, New burners, New Cast iron cooking grates, New ignitor and Flavorizer bars. When its all said and done I'll have over $250 in it. But then it should be good for a long time.
My advice- be patient. Pick up an easy one to do first that you can sell after you find what you really want.
Be sure to look for frame rust. Be sure to look at the cross fire ignition tube - lots of those are burned out.
Be sure to look under the grill at the rails that hold the catch pan on and the catch pan itself. They rust out much faster than the rest of the grill.
I have ordered pars off Ebay, Amazon and from Weber directly - just shop prices.
this site is awesome for manuals
http://outdoorcooking.manualsonline.com/manuals/mfg/weber/weber_product_list.html
EReplacement parts for exploded diagrams.
http://www.ereplacementparts.com/weber-231001-genesis-3000-grill-parts-c-193079_193087_193213.html
The hardest part will be cleaning the grill and loosening any corroded nuts and bolts.
Just be patient - pliers, wd40, PB-Blaster and a rubber mallet are your friends!