I actually don’t even see a grease tray at all. It might just be the foil, which would be wild. Also looks to be missing the Catch Pan itself for the grease tray ($15-20)
Either way though, sometimes people simply line the grease tray to “protect it”, and if it does exist (hard to tell in that photo), it might be in perfect shape.
Since you’re not afraid of a project, I’d argue that you won’t need new burners at all (I’ve never had a Silver B that actually NEEDED new burners). Just wire wheel them and spray a garden hose inside them to flush. The burner tubes crossover bar could be shot though, and you may need to replace ($10).
The grates look like the Stamped Stainless Steel and you can easily wash them and wire wheel them if you want to get them back to like new.
The Flavorizer Bars are hit or miss. If they’re stainless steel, you have a pretty good chance to still use them.
I would say $70 is fine if it has a grease tray without holes.
Also, a lot of times the side burner on those older models will have a huge yellow flame. This is due to insect webs or nests inside the tube. You can disconnect it and use a pipe cleaner and garden hose to spray it out to get it back to working like new if you need to.