According to legends (that is a lighthearted attempt at humor) doris day used to coat herself from head to toe with vaseline - hence her youthful appearance well into her senior years. My mom would coat her hands and feet with vaseline nightly (because of Doris Day) and wear kid gloves and socks to bed - and her skin was amazing. so yes, vaseline can be an inexpensive way to help retain moisture.
On the other hand, vaseline really creates a barrier so some people might run into issues with clogged pores if used regularly on their face. if it's working for you - no reason to stop - I would simply suggestusing a very thin layer - a little goes a long way.