Can you help my tank out?

Kk ill try to be quick here. Yes, the wood from your plum tree will be fine for your tank. You will need to prepare the wood prior to inserting it into your main tank. The method you stated should be done then place the wood with an anchor in a seperate tank with no fish to set and cure for around 1-2 months. Driftwood releases tannin. This lowers the pH in your tank and changes the water appearance. By leaving it in this secondary tank you are ensuring that the major part of the tannin is leaked out and before placing it into your aquarium. The wood will still give on some tannin the length of its life, however after around 2 months the amount will be so minute it wont make a large enough difference to matter. Be sure not to use varnish on the wood. Suckermouth type fish like plecos will eat on the wood and if they consume this varnish it will kill them. The main reason drift wood is so expensive has alot to do with where it originated from, but alot is just the process of curing and preparing it. I agree that its much cheaper to do yourself. Best of Luck and hope your driftwood looks wonderful.