So I just heard about Amazon opening up a new website strictly for supplies for all industires. Intrigued I checked it out to see what i could get for cheap... to may surprise there was a lab section and I then searched for anything made of borosilicate glass on the side filter. HOLY COW, they are selling by the case rod tube i've only got a few pages in but I was so amazed I had to share and maybe more eyes can find more deals than I.

amazonsupply.com

Amazon Supply - Boro Search