The most valuable piece of equipment I own!
I work in radio and record voiceovers for a living and because of that I'm used to having certain equipment at all times. It wasn't until I decided to build my own home studio that I realized just how much I relied on my VU meters at work. After attempting to mix by ear and then by attempting to use meters I found within Pro Tools with NO success, I decided that no matter how much they cost, I needed a set real VU meters. Not loudness meters .. analog VU meters.
This set is compact and portable so if you're recording on the go, you can take them along. They were a little difficult to calibrate at first but once I had them set, they've been a lifesaver.
Don't chance ruining your production by trying to mix the levels by ear or by using unreliable loudness meters. Go with the analog standard. You won't regeret it!