Brightech Ambience Pro Solar Powered Outdoor String Lights, 48 Ft Commercial Grade Waterproof Patio Lights, 15 Edison Bulbs, Shatterproof Led String Lights for Outside, Porch - 1w Warm White ...

The core of my ambient lighting system is inexpensive LED rope lighting. I purchased my LED rope lights for ~$8 per 18 foot strand. Here's a 12-footer for under 10 bucks on Amazon.