I've used tygon in the lab, and I've found stashes years (decades?) old that are still soft, flexible, and new-feeling.
Vinyl tubing seems to harden with age/use.
I've never bought tygon, so I've no clue where to get it or how expensive it is. Standard Vinyl tubing can be found at most hardware stores.
It might be worth looking into silicone tubing, I've seen some for sale in auto shops, and it's going to be more expensive, but should stay soft/flexible longer, and be more chemically/heat resistant (not really a concern for us, but...)