I, too, would like such an option for mine.

I would recommend asking a local place that does reupholstery for a quote. The design looks very simple, and I would not expect a upholsterer to charge you that much for that type of design. You would probably need to bring one of the chairs in for them to measure and fit the covers, though.

I work for a Knoll dealer and YES they are very expensive (worth it though). Could you maybe try Design Within Reach? I know that they often make knock offs of items; i'm unsure if they have something similar to Bertoia though. Otherwise, I would just take the piece to an upholstery shop and see what they can do. You'd be surprised by their ingenuity!

We had these chairs in our playroom growing up and they were always covered (lilac in the 80s!).

I have other Knoll chairs too (Saarinen Executive Chair with wood legs) that I've had to re-upholster recently. I was told by the independent upholsterer that it's safest to use the Knoll fabrics. Apparently, some fabrics are not as well suited to the unusual shapes and contours of the chairs and can rip or at least not lay correctly. So seeing that this was something we were only going to do once, it was worth the extra price.

The Bertoia chair though is simpler--the Saarinen chair has the hole in the middle--so maybe another fabric is ok. Ask a qualified Knoll upholsterer for advice.

I've tried a few different knock-offs, the fit is decent but not great. Considering how stunning the chairs are, I think it's worth it to splash out on the real deal (which is saying something, because I'm usually super thrifty). I have a set of six that I'm saving up to re-cover. In the meantime, I've picked up some inexpensive chair pads that are working just fine and don't look like total trash.

Def contact a local upholsterer and shop around for the most experienced, knowledgeable one. Consider the contours of the chair and 'metal'ness of it when choosing your fabric, ie something that will hold up against such surfaces. Best of luck!

Here are two options I have found through past AT posts. Can't vouch for the quality though:

http://www.bertoiapads.com/

http://stores.advancedinteriordesigns.com/-strse-563/bertoia-seat-pad%2C-only/Detail.bok

DWR carried the original Knoll manufactured chairs and pads, you could check with their Annex in NJ and see if they have any pads available at a discount. If you aren't in the NY/NJ area you can call them and have them shipped. AT just had a post the other week about crocheting Eames wire chairs, don't see why that same treatment wouldn't work on the Bertoia chairs.
http://www.apartmenttherapy.com/la/furniture-design/diy-midcentury-knitted-eames-chair-160325

Good luck!

No hate mail please, from the purists. However I have a store in New Zealand, and we do reproductions... we also collect vintage originals yet they are far less encountered in our tiny country....... I digress though. We recently have fit out two restaurants with Bertoias.... full upholstery. In the past, we have zinc dipped and powdercoated Bertoias for outdoor use, and had a 'sunbrella' branded cover made [ identical to originals ] so that they are all good to be used and left outside in the elements. That aside though, easy to have the covers made - take it to an upholsterer, or an automobile upholsterer..... they're not a complex fit. Short of that, talk to the guys at New Jersey Modern [ Sebastian ] and tell him that Homage in New Zealand sent you :) They're great guys :) Good luck, and love the chairs! - Joanne

to betz0041 I don't think DWR sells knock offs.