The company I use is WesTech Rigging.
Bishop Lifting - Rigging Supplies, Slings, Fabrication & Rentals
They carry an extensive mix of lines. You need to look at the lines to verify that they will work for your needs. I have picked up Dyneema, some nylon and some doublebraid dacron (polyester) lines. I shop the cut off bin. I can sometimes find lengths that my need but are half priced because they are not 100 plus feet long.
StaySet, a brand name, is a line licensed by TEUFELBERGER Fiber Rope Corp. Not available at all sources of rope.
It's advantages are: The nice hand feel, strongest and lowest stretch polyester line available with a patented parallel fiber core and a braided cover made from a blend of spun and filament polyester. Excellent value as an ideal replacement for wire halyards.
There are similar products manufactured by competitors with similar specifications.