I can only offer failures of experience 

I tried using tightly rolled paper as a cheap stick and that broke really quickly. Then I tried PVC and that also broke. I think a lot of my problem was I doing strong strikes on a post (6x6) and the target was too strong.

For sparring purposes most schools will require you to buy through them. But if you are working with friends at home simple boffer weapons with generous padding will probably suffice.

For work on inanimate objects, try to soften the blows. Tires are popular targets in that you can't destroy it with a stick and it has some give so won't destroy your stick too fast. Experiment with padding your sticks and some sort of softer target unless you're just doing targeting drills.

Find out where your local SCA guys get their Rattan. See about getting some of that to practice with. It's fairly sturdy and, if wrapped with duct tape, won't produce dangerous splinters when you break it.

Sounds good. I might still wrap the heavy bag in something to protect it.

It's a funny ol' world. To practice using a weapon, we have to protect the target from the weapon and the weapon from the target.

I own what Thearos posted. They are on the long side for Escrima and you wouldn't need the hand guards, we use them for light sabre practice and for single stick. Purpleheart is a wonderful company, I can't say enough good stuff about them.