I have been running a LN node for 1 year now and the answers to your question do depend on what type of node you run and what you're using it for. My goal was to learn Lightning, self hosting and also be able to make my own LN payments in a sovereign way through my own node.

The initial investment of time was to research the different options available for running a node and decide on which was for me. As my goal is learning I went the hands on method of purchasing a server, setting up Ubuntu on it them running both Bitcoin Core and LND on that. Cost was about USD$350 for a used Dell Optiplex. I followed the Ministry of Nodes guides on YouTube for that. There was quite a bit of time required to go through and set it all up, say up to 10 hours or so.

Once it was running the other costs have only been to fund the channel and as my purpose was to host my own payments, I did this with people I know personally who already run nodes. They helped my out by opening channels to me, then we rebalanced.

A year into this the main costs in time are to update the software packages when required, which only happens every few months.

Monetary costs required have been minimal, just funding or rebalancing channels when I run out of liquidity on my side. This costs as much as you need to spend, usually I keep a couple of hundred thousand sats in liquidity on my side of channels so I can spend as I need.

It does depend on what your goals are, if there's someone you know who's running a node they can be a great help so I would recommend hooking up with someone in your community if you can.

Hope this helps and good luck.