There are two primary parts that may need attention.
First, if you get a model with the air filter, is the filter cartridge. It’s difficult to estimate how often the filter cartridge needs to be replaced because it depends not just on how much you use it but on the material you use. Hardwoods aren’t very taxing but plywood might be, depending entirely on the glue (which is usually hard to figure out). It’s just going to vary a great deal, with light users pushing past a year between changes, and heavy users who are cutting nonstop turning them over as often as every month or so. We’re working on filter pricing, but we expect it’s going to come in under $250.
Second, for every model, is the tube. The Glowforge tube is custom made - it’s bigger than most desktop units (850mm) and has some modifications for longer lifetime and smaller spot size. It’s rated by the manufacturer for 2 years, but we’re doing lifetime testing now to dial that in a little more closely. The tube is covered under the warranty. Out of warranty, we’ll replace it and realign it for you for $499, including roundtrip shipping in the US. We’ll also have a replacement tube part available for purchase.