I have a bipod painted with Krylon, it has held up great. The only scratches are on the feet and where the bipod legs rotate down. If you want cheap and easy you cannot beat the extra flat camo paint. Just remember use a LIGHT coat, allow to dry and reapply to desired thickness. You won't get the full durability until a week later IIRC.

For a more long term solution I would stick to Cerakote. I have two bolt guns done in it and the finnish is quite tough.