There are other sizes of pipe available. Schedule 80 is twice the wall thickness of 40. There is also "double extra strong" that has much greater wall thickness. Also if standard pipe diameters are not what you are looking for then you can go with mechanical tubing. I've used some 3.5" x .625" wall DOM that was really great to machine and took a weld much nicer than pipe. Go to ALRO.com and search under tubing. It will give you an idea of the material available at least. You can also get some pricing just to see if your local steel supplier is in the ballpark.
You can save some money by having the tines flame, plasma or laser cut rather than water jet. WJ pieces have a really nice finish and tolerances are tight, but in my experience more expensive than other methods and in this case as long as all the tines are identical, a moot point. Maybe look at using AR400 or AR500 plate for the tines, since you are not machining them, this harder material will give you longer life than a HR A36 or CR steel.
