I have several hundred feet of new high pressure reinforced silicone tubing for sale. It's made by Helixmark, 0.50" ID by 0.80" OD, VWR catalog number 55566-108.
https://us.vwr.com/store/catalog/product.jsp?product_id=4640006
It can handle 430 PSI at 70 degrees F, and can withstand...