ISFETs, can they be bought cheap yet? Other cheap PH meaurements?

I am finding ph sensors expensive! I was hoping the ISFET would prove cheap but I think they might be too new?

Are there any other thoughts on ph sensing on the cheap? Not really looking to fab sensors as they seem rather involved. Glass tube electrodes are pricey and seem pretty sensitive to lots of things.

No replies on this so I thought I would bump it?

Anyone have any experiences at all with ISFETs? Hard for me to weight the pros and cons of these technologies other than the ISFET sure sounds like a lot smarter device for our needs which is less accuracy traded for longer life. Not yet sure how price plays in here.